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L. > •
A NEW SYSTEM
OF
CHEMICAL PHILOSOPHY.
' PART FIRST.— VOL. II.
NEW SYSTEM
OF
CHEMICAL PHILOSOPHY.
PART FIRST
OF
VOL. II.
BY
JOHN DALTON, F.R.S.
President of the Literary and Philosophical Society, Manchester;
Corresponding Member of the Royal Academy of Sciences, Paris;
Member of the Royal Academy, Munich, and of the Caesarean
Natural History Society, Moscow ;
Honorary Member of the Royal Medical Society, Edinburgh,
and of the Philosophical Societies of Bristol, Cambridge,
Leeds, Sheffield and Yorkshire.
Printed by the Executors of S. Russell,
FOR
GEORGE WILSON, ESSEX STREET, STRAND, LONDON.
1827.
TO
JOHN SHARPE, Esa. F. R. S.
OF STANMORE, MIDDLESEX,
(Late of Manchester)
AS A TESTIMONY OF HIS FRIENDLY REGARD, AND OF HIS
LIBERAL ENCOURAGEMENT GIVEN TO THE PROMOTION
OF CHEMICAL SCIENCE:
AND TO
PETER EWART, Esa.
Vice-President of the Literary and Philosophical Society of Manchester,
ON THE SCORE OF FRIENDSHIP,
BUT MORE ESPECIALLY FOR THE ABLE EXPOSITION AND
EXCELLENT ILLUSTRATIONS OF THE FUNDAMENTAL
PRINCIPLES OF MECHANICS,
IN HIS ESSAY ON THE MEASURE OF MOVING FORCE^f
THIS WORK IS RESPECTFULLY INSCRIBED BY
THE AUTHOR.
+ Manchester Memoirs, Vol, II. ( second series. J
PREFACE.
J. HE work now submitted to the public was begun to be printed in 1817; and the 13th and 14th sections, containing the oxicles and sulphurets, were printed off before the end of October of the same year. The printing of the rest of the work to the appendix was finished in September, 1821. One sheet of the appendix was printed at the end of 1823 ; but no addition was afterwards made till May, 1826 ; when the print- ing- was resumed, and has been continued to the present time. It may be asked, what were the motives for such a plan of procedure. To this it may be replied, that soon after the publication of the first volume (in 1810), I began to prepare materials, and to institute experiments, relating to the oxides, &c, with occasional diversions into other departments of chemistry, as circumstances arose. As a great portion of my time was always necessarily engaged in professional duties, and as that part of the work I was about to commence was one running into detail, I thought it would be best to print it as I proceeded, whilst the train of thought and of experiments was fresh in view. The advantage in this case was expected to be partly at least counterbalanced by the loss of discoveries and improvements likely to be made in the interval between the printing and publishing of the several articles. This I was aware of; but as a principal object I had in view was to
VI. TREFACE.
give the results of my own experience, in the various depart- ments of chemical science, rather than to form the best com- pilation of Chemistry at the period, this object was most likely to be obtained by the proposed plan. It is true the time the work has been in the press has far exceeded my ex- pectation; notwithstanding this I am not conscious of any very material alterations or additions, which I should wish to make at the present moment.
It affords me great pleasure to acknowledge the assist- ance I have had during the progress of this volume, from a valuable selection of chemical apparatus, for which I am indebted to the generosity of Mr. Sharpe; also the continued and friendly intercourse with Dr. Henry, whose discussions on scientific subjects are always instructive, and whose stores are always open when the promotion of science is the object.
My present design is to add a second part to this volume, and with that to finish the work. It will eonsist of the more complex compounds. Acids, and other products of the ve- getable kingdom, Salts, &c, will form principal parts. Already I have a stock of experiments on these subjects; but I am not satisfied without exploring this region afresh,
August, 1827. *-*®*
CONTENTS OF VOL. II.
Part First.
Page,
Chap. v. — compounds of two elements.
Section 13. Metallic Oxides.... 1
Oxide of Gold 5
•J Platina H
. : Silver • ••• 17
Oxides of Mercury 1*
Oxide of Palladium 24
Oxides of Rhodium, Iridium, and
Osmium. ... • 26
Copper * 26
Iron 28
Nickel 34
Tin 36
Lead 39
Oxide of Zinc .. «*i
Oxides of Potassium 53
Sodium , 56
Oxide of Bismuth 57
Oxides of Antimony 58
Oxide of Tellurium 62
Oxides of Arsenic 63
Cobalt 68
Manganese * 7i
. Chromium 80
— — — Uranium 86
— Molybdenum 87
Tungsten 90
. Titanium. 91
Columbium 92
Cerium 94
X. CONTENTS.
Pa©?
Section 14, Earthy, Alkaline, and Metallic SuL
pliurcts 96
Siifphurets of Li?nc 99
Sulphuret of Magnesia Ill
Sulphurcts of Barytes 112
Stroniitcs 114
Alumine, Si lex, Yitria,
Glucine etncl Zireonc ... 114
._ — Potash :..;.; 116
■ ■-■ — Sbda..... 119
Sulphuret of Ammonia 120
Sulphurots of Gold...,, ,. 121
Sulphuret of Platina. 123
Sulphurets of Silver 126
"• — Mercury 127
Sulphuret of Palladium 131
- — / ' Rhodium 132
'•'""" ' '" " Iridium 132
- - lll ■- — Osmium 132
- Sulphurets of Copper ... 133
* — — - — — — Iron 134
' Nickel 138
— — —Tin 139
— Jbead. 144
— — Zinc 146
► Potassium and Sodium ... 148
Bismuth 149
Antimony 151
Sulphuret of Tellurium 153
Sulphurets of Arsenic 153
Sulphuret of Cobalt , 160
Sulphurcts of Manganese 162
Sulphuret of Chromium 163
Uranium 164
-r — Molybdenum 164
Sulphuret of Tungsten 1 64
CONTENTS XI.
Page.
Sulphur cts of Titanium, Columbium, and Cerium .... 165
Section 15. Earthy, Alkaline, and Metallic Phos- phurets 1 66
PJwsphurct of Hydrogen 169
Phosphurets of Carbon and Sulphur 184
Phosphuret of Lime.... 184
. Barytcs ._ 188
Strontites ............. 190
Gold 191
— — Platina 194
_ , Silver 195
1 Mercury 197.
Palladium 198
Copper.. 199
— Iron ... 201
Nickel , 201
— Tin ....s 202
— - Lead 203
Phosphurets of Zinc and Potassium ...... 204
Sodium and Bismuth ....... 207
— Antimony and Arsenic ..'.• 208
Phosphuret of Cobalt % 209
Manganese * 210
Section 16. Carburets.... 211
._ of Iron... steel 212—214
Section 17. Metallic Alloys 218
Alloys of Gold, with other metals.... 222
Platina, with other metals 226
— Silver, with other metals... 228
Mercury, and other metals .
amalgams 230
Triple, Quadruple, fyc. amalgams ... 236
Alloys of Copper, with other metals 238
Iron, with other metals ... 253
Alloys of Nickel and Tin, with do.. t, 254
Lead, ivith do. 258
Xll. CONTENTS.
Section 17. Triple Alloys, Solders ; fusible metal, dfc. 203
APPENDIX.
Abstract of De hi Roche and Bcrard's essay on the
specific heat of gases 268
Du yong and Pctitfs essays,
On the expansion of air, mercury, glass, iron, copper, and plettina, by heat 272
On the capacities of certain bodies, for heat 274
On the laics of refrigeration *...., 277
On the specific heats of certain bodies 280
Remarks on the above essays 282
New Table of the forces of vapours 298
Table of the expansion of air, and the force of aqueous and tethcrial vapour, adapted to atmospheric temperatures. 299
Applications of the eibove table 300
Formulae for determining the proportions of combustible
gases, in mixtures 305
Heat produced by the combustion of gases 309
Absorption of gases by water 309
Fluoric acid — deutoxide of hydrogen 311
Muriatic acid — oxy muriatic acid 313
Nitric acid — compounds of azote and oxygen 315
On ammonia., 328
Decomposition of ammonia by nitrous oxide 330
by nitrous gas and oxygen 332
Volume of gases from the decomposition of ammonia,,, 335
Decomposition of ammonia by a red heed 335
Decomposition of ammonia by oxymuriatic acid 335
Sulphuret of Carbon 338
Potassium, Sodium, Sfc ;».. 340
Alum 311
New table of the relative weigh ts of atoms 352
Addenda. Steel ; mixed gases ; expansion of liquids
bu heat ,, .» 354
NEW SYSTEM
OF
CHEMICAL PHILOSOPHY.
CHAP. V.
SECTION 13.
METALLIC OXIDES.
^A-LL the metals are disposed to combine with oxygen, but the combination is effected more easily with some than with others; the compound is usually called an oxide, but in some instances it is also called an acid. The same metal combines with one, two, or per- haps more atoms of oxygen, forming com- pounds which may be distinguished accord- ing to Dr. Thomson, by the terms protoxide, deutoxide, trit oxide, . &c.
Such however is the repulsion of oxygen to oxygen that we rarely find three atoms of it retained by a single atom of any kind ; and there are not many instances of metals capa-
VOL. II. A
2 METALLIC OXIDES.
ble of holding two atoms of oxygen. Vari- ous modifications of the proportions of metals and oxygen arise from the combinations of the oxides themselves one with another and with oxygen, so as to lead some to imagine that an atom of metal in some instances com- bines with 3, 4, or more of oxygen. This is altogether improbable: It is much more simple to suppose that one atom of oxygen connects two or more atoms of protoxide, 1 of protoxide unites to 1 or more of deut- oxide, &c. These intermediate oxides are in few if any instances found to combine with acids like the other two oxides.
There is no reason that I am acquainted with for disbelieving that oxygen combined with a metal is still repulsive df oxygen, and that by the same law as particles of an elastic fluid; that is, the repulsion is inversely as the distance of the centres of the atoms. Hence it may be demonstrated that it re- quires twice the strength of affinity to form a deutoxide as a protoxide* three times the strength to form a tritoxide as a protox- ide> Sec; On this account it is, in all proba- bility, that deutoxides are not numerous, and tritoxides are rarely if ever found.
The quantity • of oxygen that combines
METALLIC OXIDES. 3
with any metal to form an oxide may be in- vestigated by several methods.
1st. By combustion; a given weight of the metal may be burned and the oxide pro- duced may be collected and weighed ; when the increase by combustion will appear.
2. By solution in an acid and precipitation by an earth or alkali; in this case a given weight of the metal is dissolved and precipi- tated; the precipitate collected and suffici- ently dried shews the increase by oxygen.
3. By transferring the oxygen from an oxide to another metal; in this case the me- tal in question is usually immersed in a saline solution of the other metal; this latter me^ tal gives up its oxygen to the former and is itself reformed or revived as it is termed.
4. By determining the proportion of hy- drogen gas evolved during the solution of a given weight of metal; then allowing half of that volume for its equivalent of oxygenous gas, the weight of it shews the oxygen united to the metal; it being now well understood that water furnishes the two elements of hy- drogen and oxygen in such case.
5. The higher oxides are conveniently de- termined by the application of the solution of oxymuriate of lime to the lower oxides in. solution.
4 METALLIC OXIDES.
6. The quantity of oxygen in several ox- ides may be found from the quantity of ni- trous gas evolved during the solution of a given weight of metal in nitric acid.
The first four methods have been used by chemists for several years past; the two last
1 have added from my own experience, hav- ing found them very useful assistants in vari- ous instances. The last method by nitrous gas, has indeed been proposed before, and la- bour bestowed on it both by others and my- self, but without reducing the results to any certainty, till lately ; the principal cause of this want of success has arisen from misunder- standing the nature and constitution of nitric acid. Most chemists seem with me to have mistaken nitrous acid for nitric ; the former is composed of 1 atom of azote and 2 of oxygen ; or perhaps of 2 azote and 4 oxygen ; the latter of 2 azote and 5 oxygen, or 2 nitrous gas and 3 oxygen ; the weight of the former is* 19, or its double 38, on my scale, and that of the latter 45. [My reasons for adopting the above conclusion respecting nitrous acid, which is at variance with that in Vol. 1, p. 331, will be given hereafter.] When there- fore a metal is oxidized by nitric acid, 3 atoms of oxygen (= 21) go to the metal, and
2 atoms of nitrous gas (= 24) are disengaged.
METALLIC OXIDES. 5
Hence \ of the weight of nitrons gas evolv- ed is the weight of oxygen combined. It sometimes happens however that the nitrous gas is partly or wholly retained by the residue of nitric acid ; but in this case the oxy muriate of lime can be applied to convert the nitrous gas into nitric acid, and from the oxygen im- bibed the quantity of nitrous gas may be in- ferred.
1. Oxide of Gold.
Some difficulties have been found in ascer- taining both the number and proportions of the oxides of gold; hence the differences in the results of authors.
Gold does not burn by exposure to heat, but gold leaf and gold wire may be deflagra- ted by electricity and galvanism ; a purple powder is the product, which is considered by some as the protoxide of gold ; but others, after Macquer and Proust, conceive with greater probability that this powder is no- thing but gold reduced to its ultimate divi- sion. Solutions of gold which are of a fine yellow, give a purple stain ; and gold deoxi- dized by green sulphate of iron is precipita- ted blue, which precipitate gradually as- sumes a yellow colour as the particles become
6 METALLIC OXIDES.
united. The very weak affinity of gold for oxygen is shewn by the difficulty with which it is oxidized and the ease with which the oxygen is expelled again by heat; these facts seem to preclude the idea of gold com- bining with oxygen in high temperatures.
Protoxide. Gold is scarcely affected by pure sulphuric, nitric or muriatic acid; but it is easily oxidized and dissolved by nitro- muriatic acid (that is, a mixture of nitric and muriatic acids) when assisted by a tem- perature of 150 or 200°. Caustic potash be- ing put into the solution and heated, a brown- ish black precipitate is obtained; but a part of the oxide remains in solution combined with the muriate of potash, according to Vauquelin ; and Proust has observed that the oxide cannot be washed and dried in a mode- rate heat without a portion of the gold being revived; hence the difficulty of ascertain- ing in this way the weight of oxygen com- bining with gold.
I have succeeded, as I apprehend, in de- termining the relative weights of gold and oxygen, by two methods, which mutually corroborate each other. The first is by means of th# nitrous gas generated by the solution of gold ; and the second is,* by find- ing what quantity of green oxide of iron is
METALLIC OXIDES. 7
converted into red by precipitating a given weight of gold in solution.
Ten grains of guinea gold of the sp. gr. 17.3, were repeatedly dissolved in a small excess of nitro-muriatic acid; the quantity and purity of the nitrous gas generated were duly observed and allowance made for the loss occasioned by a small portion of common air originally in the gas bottle. The volume of nitrous gas corrected as above was always found between 1100 and 1200 grain measures, the weight of which may be estimated at J .6 grains, corresponding to 1.4 grains of oxygen. The small portion of alloy (XV) known to be in standard gold is chiefly copper with a small part silver; now it will be seen in the sequel that copper takes ~ of its weight of oxygen ; hence if we allow .8 of a grain for copper and .2 for the oxygen combining with it, we shall have 9.2 gold united to 1.2 oxygen, or 100 gold with 13 oxygen, which is nearly the same as Berzelius has determined by precipi- tating the gold by mercury.— Again, 10 grains of gold were dissolved as above (= 9.2 pure) and precipitated by a solution of pure green sulphate of iron of the sp. gr. 1.181 and which I had previously proved to contain 9 grains of green oxide in 100 measures. They converted 120 measures of this green
8 METALLIC OXIDES*
sulphate into yellow, which was carefully precipitated afterwards by lime water, dried and weighed. The gold precipitated was found very nearly 9 grains; and the yellow oxide of iron mixed with oxide of copper was nearly 13 grains. Now 120 measures sulphate iron contain 10.8 grains green oxide, and these require ~ of their weight of oxy- gen (see the oxides of iron) to be changed into yellow oxide, or 1.2 oxygen. Hence it appears that the oxygen combined with the gold was transferred to the iron unchanged in quantity. It is to be observed however that green oxide of iron not only deoxidates the gold but it semideoxidates the copper also ; so that .1 of the transferred oxygen above might be said to be derived from the copper, and the rest, or 1.1 from the 9 grains of gold ; this would give 100 gold to 12.2 oxygen, which is still nearer to the determination of Berzelius. Upon the whole I am inclined to adopt the proportion of 8 to 1 or 100 to 12.5 as that which appears the most correct ap- proximation and at the same time a ratio easily remembered and adapted to facilitate calculations.
We are now to consider whether the above is the protoxide. As no other oxide has been clearly shewn to exist, and as this combines
METALLIC OXIDES. 9
with muriatic acid, with ammonia, with the oxide of tin, &c. and is wholly deoxi- dated by green sulphate of iron and by a mo- derate heat, there seems every reason to con- clude it is a combination of the most simple kind, or 1 atom of metal to 1 of oxygen. Hence the atom of oxygen being 7, that of gold must be 56, and not 140 or 200, as sta- ted Vol. 1, p. 250.
Berzelius seems to consider the above as the tritoxide, or three atoms of oxygen to one of gold; but it is extremely improbable that gold, which is allowed to have a weak affinity for oxygen, should be able to restrain the violent repulsion of three atoms of oxygen, and should on every occasion lose them all at once, and not by degrees, as is usual with other high oxides.
Subjoined are the results of various au- thors in regard to the oxide of gold, but ge- nerally given with diffidence as to their ac- curacy.
|
gold |
oxygen |
|
Bergman 100 |
+ 10 |
|
Proust |
4- 8.57 to 31. |
|
Oberkampf — — |
+ io |
|
Berzelius « |
-f 12 (4, suboxide) |
|
My results — |
+ 12.5 |
|
roL. ii. |
B |
10 METALLIC OXIDES.
Since writing the above I have had an op- portunity of repeating the experiments on the oxide of gold by an improved nitrous gas apparatus, calculated almost entirely to ex- clude atmospheric air; I find less nitrous gas produced during the solution than stated above, sometimes by 4, and that it is variable according to the excess of nitric acid ; also that the solution requires a portion of oxymu- riatic acid as an equivalent for the nitrous gas retained. I prefer, however, the method of oxidizing the green sulphate of iron; by putting a small excess of the green sulphate and precipitating, first the red oxide and then the green, I obtained very distinct results. On the whole I am inclined to think my re- sults preceding these have rather overrated the oxygen, and that it would as nearly be stated at 11 on the hundred. This would be nearly a mean of those in the above table, and would require the atom of gold to be 63, and that of the oxide 70. Between the two extremes of 56 and 63 it is most probable the true weight of the atom of gold will be found.
It may be proper to add that I have found 100 grain measures of muriatic acid (1.16), and 25 of nitric (1.35), are sufficient to dis- solve 40 grains of standard gold; and I have
METALLIC OXIDES. 11
reason to think the acids are in due proportion nearly, though different from what is usually recommended and employed.
2. Oxide of Platina.
Platina exhibits greater difficulties than gold in the investigation of its compounds with oxygen. It is not oxidized by heat; but by the explosion of an electric battery it is converted into a black powder, which is most probably the metal in extreme division, though it has been considered by some as the protoxide. Platina is capable of being oxi- dized and dissolved by nitro-muriatic acid, but less easily than gold; it requires more acid, as high or higher temperature and long continued digestion; nitrous gas is given out, during the solution, but sparingly. When lime or an alkali is added to the solution with a view to precipitate the oxide, a tri- ple compound is usually formed of the acid, the oxide and the alkali, which is in most instances precipitated. This weighty com- pound renders the valuation of the oxygen in it very uncertain.
Chenevix has made some observations on the oxides of platina, (see Nichols. Journ. 7. p. 178.) He finds two oxides: the one con-
12 METALLIC OXIDES.
sists of 93 platina and 7 oxygen; the other of 87 platina and 13 oxygen; but the expe- riments on which these results rest are not quite satisfactory.
Mr. E. Davy in the 40th vol. of the Philos. Magazine, states his having reduced the oxide of platina in solution by means of hy- drogen ; and that he finds the oxide to consist of 84 platina and 16 oxygen nearly. I could not succeed at all in effecting the reduction of the metal in this way.
Berzelius has lately given us the results of his investigation on this subject. (An. de Chi- mie 87-. — 126.) According to this distinguished chemist there are two oxides of platina; the first consists of 100 metal and 8 J oxygen, and the second of 100 metal and 16| oxygen* nearly. In order to understand his process it may be proper to premise that when nitro-mu- riatic acid has dissolved as much platina as it can, there is still a great excess of one or both of the acids, which is unnecessary for the existence of the solution, and which may, and in general ought to be expelled by evaporation; by exposing the solution to a heat of 100 or 150° the excess of both acids is in great part driven off and a dry red mass is obtained, without smell, but very deliques- cent. It is equal to or rather more than twice
METALLIC OXIDES. 13
the weight of the platina. It consists of wa- ter, muriatic and nitric acids, oxygen and pla- tina; it is still an acid salt. By exposing the dry mass again to a heat of 400 or 500°, it liquifies, exhales acid fumes having the odour of oxymuriatic acid, and becomes again a dry mass of an olive colour, exhaling fumes as the heat increases, and loses about J of its weight. It is still soluble in water, except a few atoms of black powder, continues acid to the tests, and may be considered as a su- permuriate of platina. If this olive powder be again heated almost to red, it exhales a vi- sible smoke in the open air, which has the smell of oxymuriatic acid, and becomes a light brown powder, having lost a little weight. It is then neither deliquescent nor soluble in water except in a small degree so as to give the yellow colour. In this state it has been considered as a neutral muriate. By a moderately bright red heat this powder is decomposed and leaves a black spongy mass which is found to be pure platina.
The insoluble muriate of platina according to Mr. E. Davy, contains 72.5 per cent, of platina, and Berzelius finds 73. 3j the loss is considered as oxymuriatic acid ; hence from the known proportions of this acid Berzelius infers the constituents of 100 muriate=73.3
14 METALLIC OXIDES.
platina, 6.075 oxygen and 20.625 muriatic acid ; or 100 platina take 8.3 oxygen. The near agreement of the above authors is favour- able to the accuracy of their results; but I have found some difficulty in obtaining the insoluble muriate free from the soluble one, and at the same time from reduced platina because the precise degree of heat requisite to produce it is neither well known nor easily attained; and it is desirable that a certain weight of platina should be dissolved and the same weight reproduced as a confirmation of accuracy. From a train of experiments on the soluble and insoluble muriates of pla- tina, the salts being obtained from the puri- fied laminated metal, I am disposed to consi- der the above results as good approximations to the truth.
In order to obtain the other oxide, Berze- lius digests mercury in a solution of the super- muriate of platina; a black powder is thrown down, which is found to be platina, and mer- cury is taken up, being oxidized at the expence of the platina. It was found that 16.7 grains of mercury had precipitated 8.5 of platina; and the mercury being calculated as in the state of deutoxide, contained, from the known proportions of this metal, 1.4 oxygen; hence 8.5 platina must have yielded 1.4 oxygen;
METALLIC OXIDES. 15
and if 8.5:1.4:: 100:16.4; so that 100 platina must have had 16.4 oxygen in the supermuri- ate, or twice the quantity it had in the inso- luble muriate.
This conclusion appears to me premature; the mercurial oxide should at least have been precipitated and a corresponding quantity have been found and proved to be the red oxide. Even had this been the case, it is not easy to determine what quantity of it might be due to the residue of nitro-muriatic acid. But I have not found that the common yellow or red oxide of mercury is precipitated by lime water in such case; the precipitate is brown, and evidently contains both mercury and platina. Proust had found in his excel- lent essay on platina (Journ. de Physique 52 — 437, 1801) that mercury decomposes mu- riate of platina, that an amalgam of platina with a little calomel, and much mercury in powder, were precipitated ; exposed to heat, a fine black powder was left which had the characters of platina. Into a solution of pure platina that had been evaporated to dry- ness in 150° and redissolved, I put 9 J grs. of mercury, and boiled it for 10 minutes in a glass capsule, till there was apparently no further change; the liquor filtered was as yellow as at first; the mixture of black powder and
16 METALLIC OXIDES.
running mercury remaining"' on the filter, when dried, weighed 6| grains; this heated to a low red in an iron spoon, left 1 grain of fine black powder; the liquid saturated with lime water, yielded 2| grains dry black pow- der insoluble in cold nitric acid; after this, pro- tomuriate of tin threw down 5| grains of the compound oxides of platina and tin. The so- lution at first contained 3.3 grains of platina. In another experiment 2 parts of calomel were put to 1 of platina in solution; when heated to boiling, the calomel was dissolved and a little black powder was precipitated, which did not amount to half the weight of the platina. Lime water threw down from the liquid, a yellowish olive or brown pre- cipitate, partially soluble in cold nitro-muri- atic acid; and after this, muriate of tin yielded a brown precipitate. These experiments shew that the action between muriate of pla- tina and mercury or the mercurial salts, is of a complicated nature, and is not limited to the decomposition of the oxide of platina
and the substitution of the deutoxide of mer- cury in its place.
The difficulties abovementioned have led
me to investigate the oxygen combining with
platina by means of the nitrous gas yielded
upon its solution in nitro-muriatic acid. By
METALLIC OXIDES. 17
three distinct experiments I found that 30 grains of pure platina by solution yielded nearly 750 grain measures of nitrous gas, which may be considered as 1 grain in weight ; | of which = .875 for oxygen; this would give 8.75 oxygen per cent. But from a sub- sequent experiment made under circumstan- ces calculated to preclude as much as possible every source of fallacy, I obtained 790 mea- sures of nitrous gas from 10 grains of pla- tina; and the solution afterwards took 60 measures of oxy muriatic acid gas before a permanent smell of the gas was produced. These 790 measures = 1.05 grain, \ of which = .92, to which add .04 for the oxygen acqui- red from the oxymuriatic acid, and we have ,96 oxygen for 10 platina ; or 100 platina take 9.6 oxygen. But if 9.6 : 100 :: 7 : 73, for the weight of an atom of platina, and 80 for that of the protoxide, as I apprehend it to be, and the only oxide of platina we can at pre- sent form. (The atom of platina in Vol. 1, page 248, was estimated at 100.)
3. Oxide of Silver,
When silver wire is exploded by electricity in oxygen gas, a black powder is produced, which is the oxide of silver. If silver be dis-
VOL. II. C
18 METALLIC OXIDES.
solved in nitric acid and precipitated by lime water, an olive brown powder falls which be- comes black when exposed to the light. This -black powder is the only oxide of silver with which we are acquainted. The proportion of silver and oxygen has been investigated bj various chemists; the results are as under.
silver oxygeu
Wenzel 100 4- s 8.5
Proust + 9.5
Bucholz and Rose ... 4- 9.5*
Gay Lussac. 4* 7.6 f
Berzelius , 4- 7.925
From the solution of 170 grains of standard silver T obtained nearly 30 oz. measures of ni- trous gas = 18| grains, corresponding to 16 oxygen. This would give 9.4 oxygen upon 1Q0 silver. But as TV of the metal or 17 grains was copper, and this takes -J. of its weight of oxygen, we shall have 159 silver and 1LJ oxygen, or 100 silver and 7.7 oxygen nearly.
If we adopt 7.8 as the proper quantity of oxygen on 100 silver, we shall have 7.8: 100 :: 7 : 90 nearly, which represents the weight of an atom of silver, and 97 that of the oxide.
* 7.9 when duly corrected. Annal. de Chimie, 78—114. t Memoirs d'Arcueil 2—168.
METALLIC OXIDES. 19
4. Oxides of Mercury.
Two oxides of mercury have been long known and are well distinguished from each other. They may be obtained by exposing mercury to a heat not exceeding 600% in con- tact with oxygen gas or atmospheric air, and due agitation ; but this method is rarely adop- ted in practice. A high degree of heat de- composes the oxides again.
Protoxide. To obtain the protoxide, mer- cury must be slowly dissolved in dilute nitric acid without heat, and an excess of mercury must be used. If to 1000 grain measures of nitric acid, 1.2 sp.gr. be put 500 grains of mercury, by occasional agitation the requi- site solution will be obtained in 24 hours. A portion of this solution must be treated with a small excess of lime water or caustic alkali, when a black powder will be thrown down, which is the oxide containing a minimum of oxygen, and hence may be considered the protoxide.
Deutoxide. If to 1000 measures of nitric acid, 1.2 sp. gr. be put 350 grains of mercury, and the mixture be boiled till the mercury dis- appear, a solution will be obtained contain- ing the deutoxide. A portion of this being treated as beforementioned with lime water, a yellowish red powder is precipitated, whicn
20 METALLIC OXIDES.
is the oxide of mercury containing a maxi- mum of oxygen; all the later authors agree that it contains just double the quantity of oxygen to a given portion of mercury that the former does, and may therefore be called the deutoxide.
These two oxides combine with most acids and form salts, some of which exhibit re- markable differences occasioned by the ox- ides; thus, muriatic acid with the protoxide forms protomuriate of mercury, commonly called calomel, an insoluble salt; with the deutoxide it forms deutomuriate of mercury, commonly called corrosive sublimate, a solu- ble salt.
The proportions of metal and oxygen in the two oxides may be found by precipitating a known weight of mercury reduced by solu- tion to either of the oxides, then drying and weighing the oxides, when the increase of weight by the addition of oxygen may be ob- served. This method is less accurate with re- gard to mercury than to other metals, on ac- count of the very great weight of the atom, by which a small error in the gross weight of the oxide will be a great one as it respects the oxygen. This circumstance will partly account for the differences of authors on this subject.
METALLIC OXIDES. 21
One fact has been for some time known which demonstrates the oxygen in the red oxide to be double that in the black. Cor- rosive sublimate may be reduced to calomel by adding to it as much mercury as the sub- limate contains, and triturating the mixture well, the oxygen of the red oxide (as well as the acid) becomes equally divided amongst the mercury and forms the black oxide, which is a constituent of calomel. Hence it fol- lows that if the oxygen in one oxide can be ascertained, that of the other becomes known. Or if we can find how much oxygen must be added to the black oxide to change it to the red, we shall know the oxygen in both. Conformably with this last idea I have found a very accurate and elegant method of ascer- taining the oxygen required to convert the black to the red oxide by treating protomu- riate of mercury, mixed with water and a lit- tle muriatic acid, with oxymuriate of lime in solution; this must be gradually added till the protomuriate is dissolved,- or rather con- verted to the deutomuriate. The quantity of oxygen in a given solution of oxymuriate of lime is most conveniently found by a solution of green sulphate of iron, : as will be shewn under the' oxides of that metal.
The oxides of mercury may be investigat-
22 METALLIC OXIDES.
ed by the nitrous gas produced during solution. When mercury is dissolved without heat, as mentioned above, no nitrous gas is liberated. The solution has a strong nitrous smell and requires a great quantity of oxy muriate of lime to saturate both the oxide and the acid. When heat is employed to accelerate the so- lution, nitrous gas is liberated. I dissolved 154 grains of mercury, in nitric acid, 1.2 sp. gr., by the application of a gentle heat from a lamp. About ^ excess of acid re* mained in the solution; the nitrous gas ob- tained was 12 oz. measures =7.5 grains, cor- responding to 6.5 oxygen, which gives nearly 4 oxygen or 100 mercury. This would have led me to suppose I had obtained the black ox- ide in solution ; it was however entirely the red, as it gave no precipitate by common salt, and exhibited the red oxide by lime water; but it required as much oxymuriate of lime as contained 6.5 oxygen to saturate the nitrous gas in the solution before any oxymuriatic acid was liberated. It was clear therefore that only | of the nitrous gas was evolved, and the other § was retained in the solution, though it had been exposed to boiling heat.
The following are the proportions assigned by the several authors for the oxides of mercury.
METALLIC OXIDES. 23
Mercury. Oxygen.
^ %
black. red.
Bergman* 100 + 4 +
Lavoisierf H •jr 7.75 to 8
Chenevixj — - +12 + 18.5
Taboada|| + 5.2 + 11
Fourcroy & Thenard (a) + 4.16+ 8.21
Sefstrom (6) + 3.99 + 7.99
My results give + 4.2 + 8.4
Though the relative weights of oxygen and mercury may be investigated as above, yet it is from the weight of mercury and the acids in the salts of mercury, some of which are of a very definite character, such as the muri- ate and the deutomuriate, that the relative weight of the atom of mercury is best inves- tigated. From these I first deduced the weight of an atom of mercury to be 167 about 10 years ago, and subsequent experi- ence has not induced me to change the num- ber, though it probably may admit of some correction. If the atom of mercury be deno- ted by 167, that of the protoxide will be 174,
* Kirwan's Mineralogy.
t Annals of Philosophy, Vol. 3, p. 333.
1 Philos. Trans. 1802.
|j Jour, de Physique. 1805.
(a) Mem.d'Arcueil,Vol.2.p.l68. 1809.
(b) Annals of Philosophy, Vol.2, p. 48.
24 METALLIC OXIDES.
and that of the deutoxide 181 ; which makes 100 mercury take 4.2 and 8.4 oxygen for the oxides respectively, as in the above table.
5. Oxide of Palladium.
The discoverer of this metal, Dr. Wollas- ton, has given us its distinguishing chemical properties ; but we are indebted to Berzelius and Yauquelin for the proportions of oxygen and sulphur which combine with the metal (Vid. Annal. de Chimie, 77 arid 78.) Few chemists have had an opportunity of making experiments on this metal, owing to its great scarcity and the consequent high price of it (1 shilling per grain). It does not seem de- sireable that any but those skilled in the more delicate chemical manipulations should ope- rate upon articles such as the present.
Berzelius treated the muriate of palladium with mercury, which abstracted the oxygen and left an amalgam of palladium and mer- cury ; from the quantity of mercury dissolved he calculates that 100 palladium combine with 14.2 oxygen. This conclusion was cor- roborated by the circumstance that 100 palla- dium were found to take 28 of sulphur, or double the quantity of oxygen, which fre- quently happens with the metals.
METALLIC OXIDES. 25
Vauquelin precipitates the oxide of palla- dium from the muriate by potash; it appears of a red brown colour, and is probably a hy- drate ; when washed and dried in a moderate heat, it becomes black, it loses 20 per cent, by a red heat and becomes metallic. This would give 25 oxygen on 100 metal ; but as he finds the sulphuret to be 100 metal with 24 or 30 sulphur, nearly agreeing with Berze- lius, it is very probable that a moderate heat does not free the oxide from water, and that consequently a part of the 20 per cent, loss is water.
I dissolved 3 grains of palladium in a small excess of nitro-muriatic acid and obtained 240 grain measures of nitrous gas ; the same quantity was obtained a second time, and to the solution (slightly acid) were added by de- grees 200 measures of oxymuriatic acid gas; after agitation no smell was perceived, but by increasing the quantity of gas a perma- nent smell of oxymuriatic acid was produ- ced, and when 200 more had been added the smell was sensible for some days in an open jar, a presumption that no higher oxide is to be obtained. Now 240 nitrous gas = .32 of a grain, corresponding to .28 of oxygen, and 200 oxymuriatic acid = .64 of a grain, cor-
VOL. II. D
26 METALLIC OXIDES.
responding1 to .15 oxygen; the sum of the two portions of oxygen = .43, which must have combined with 3 grains of palladium ; if .43 : 4 : : 7 : 50 nearly. Or 100 metal com- bine with 14 oxygen, as determined by Ber- zelius. I find the sulphuret to accord with this determination; and by carefully satura- ting the excess of acid in the nitro-muriate of palladium and then finding the quantity of lime-water necessary to precipitate a certain weight of palladium, as well as the quantity of test muriatic acid necessary to dissolve the precipitated oxide, I am confirmed in the opinion that the atom of palladium must weigh 50 nearly, and its oxide 57, which there is every reason to believe is the prot- oxide.
6, 7, and 8. Oxides of Rhodium, Iridium, and Osmium.
Nothing certain has yet been determined respecting the oxygenation of these very rare metals.
9. Oxides of Copper.
There are two oxides of copper according to the results of Proust, Chenevix, Berze- lius and others, the proportions of which are
METALLIC OXIDES. 27
given nearly the same by all, and so as to leave no reasonable doubt concerning their accu- racy.
1. Protoxide. This oxide is orange, and contains 12| oxygen on 100 copper: it is ob- tained by precipitating a portion of copper from the solution of any cupreous salt, by means of iron, then mixing this copper with a rather greater portion of the deutoxide and triturating them well. This being done, the mixture is to be dissolved in muriatic acid, and the orange oxide may then be precipita- ted by an alkali.
2. Deutoxide. This oxide is black ; it con- tains 25 oxygen on 100 copper : the black oxide is obtained by dissolving copper in ni- tric or sulphuric acid, then precipitating by lime-water or an alkali, and heating the dried precipitate red hot. It may also be obtained by exposing copper to a red heat for some time in common air or oxygen gas, removing the scales and exposing them in like manner, till at length the black oxide is formed.
By dissolving 112 grains of copper turn- ings in 1000 grain measures of 1.16 nitric acid,
1 obtained 48 oz. measures of nitrous gas, = 30 grains ; by oxy muriate of lime I found
2 grains of nitrous gas in the solution, mak- ing in all 32 grains = 28 grains qf oxygen,
28 METALLIC OXIDES.
Tf 28 : 112 :: 14:56, for the weight of an atom of copper; hence the protoxide — 63 and the deutoxide = 70. These weights I adopted in 1806, and have not seen any reason to modify them since.
10. Oxides of Iron,
Two well known and well distinguished oxides of iron are now universally admitted ; the one contains 28 oxygen on 100 iron, the other 42 on 100.
1. Protoxide. This is always formed when iron is dissolved in dilute sulphuric or muriatic acid ; it may be precipitated from these solu- tions by the pure alkalies or earths ] it appears at first of a dark green, being then a hydrate or combined with water; on a filtre it soon becomes yellow at the surface by attracting oxygen ; when dried in a heat of 200° or up- wards it becomes black. The quantity of oxygen in it is best ascertained from the hy- drogen generated during the solution of the iron. All the authorities I have found nearly concur in their results as under.
100 grains of iron dissolved in dilute sul- phuric or muriatic acids yield hydrogen, ac- cording to
METALLIC OXIDES. 29
Cavendish (1766) 155 cubic inches.
Priestley, from 147 to 162
Lavoisier 163
Vandermonde, Berthollet, | max 176
and Monge y
Vauquelin 160 to 179
Dr.Thomson 163
My own Experiments give 160
Mean 164=82 oxygen^ 27.9 grains.
By precipitating the oxide, and drying it, nearly the same result may be obtained, as 100 iron will yield 128 oxide. This oxide is magnetic.
2. Intermediate or red oxide. This oxide may be obtained in various ways. First by calcining the sulphate or nitrate of iron. Second by precipitation from old solutions of the salts of iron ; the precipitate is yellow at first, being perhaps a hydrate; but when dried and heated it becomes brown-red. Third, by calcining iron or repeatedly expos- ing iron filings to a red heat, and tritura- tion. Fourth, by treating a solution of the sulphate or other salt of the protoxide with oxmuriatic acid, or oxymuriate of lime till t^xy muriatic acid is evolved; then precipitat- ing-the oxide which is thus converted into the red. Fifth, by agitating water containing the
30 METALLIC OXIDES.
green oxide recently precipitated, with oxy- gen gas. The red oxide is not sensibly mag- netic.
The quantity of oxygen in the red oxide may be investigated in various ways, and it is generally allowed that they all concur in giving 42 on 100 iron. The one which I have used peculiarly, and prefer both for ease and accuracy, is to find the quantity of oxy- muriatic acid gas necessary to saturate a given portion of the green sulphate. I take for in- stance 100 measures of 1.149 green sulphate, which I know to contain 8 grains of black oxide ; this I find absorbs nearly 13 hundred measures of oxymuriatic acid gas before the acid smell is developed ; the oxygen cor- responding to this quantity of acid is known to be near 660 measures, = .88 grain. (See Vol. 1, p. 308.) Hence, if 8: .88:: 128 : 14; or 128 black oxide acquire 14 or become 142 when converted into the red oxide. This fact being established, I find it very conve- nient to make use of the oxymuriate of lime instead of the acid gas, adopting the solution of green sulphate of iron as a test of the quantity of oxymuriatic acid in a given vo* lume of any solution of oxymuriate of lime.
The quantity of oxygen in the red oxide of
METALLIC OXIDES. 31
iron may be inferred, but not so satisfacto- rily, from the nitrous gas obtained during the solution of iron in nitric acid. In order to obtain the most gas from a given quantity of the materials, they should be so proportioned as to produce saturation nearly. If an excess of acid be used, it absorbs the nitrous gas in part; and if an excess of iron, it is not all dissolved. I took 50 grains of iron filings and 600 measures of 1.15 nitric acid; these were put together in a gas bottle and by the assistance of a little heat a quantity of ni- trous gas was obtained equal to 12 grains in weight, allowing the sp. gr. of the gas to be 1.04 (air being 1) ; all the iron was dissolved except a few atoms, and the solution was slightly acid ; the whole of the oxide was red when precipitated by lime water. Now 50 grains of iron take 21 of oxygen to form the red oxide, and these correspond to 24 of ni- trous gas, which is just twice the quantity obtained; one half of the gas generated then remains in combination with the iron, even when the constituents of the salt are pro- portioned so as to produce mutual saturation. I was in expectation that the quantity of ni- trous gas retained might be converted into nitric acid by oxymuriate of lime, and hence might be determined; but in this I was dis-
32 METALLIC OXIDES.
appointed. When oxymuriate of lime is added to the liquid, a pungent gas is libe- rated, the nature of which I have not de- termined. Thinking, it might in part be owing to the iron, I transferred the acid to soda, by decomposing the nitrate of iron by the carbonate of soda ; this nitrate of soda however, when treated with oxymu- riate of lime, exhibited the same pheno- menon as the nitrate of iron. When an acid is added the oxymuriatic acid itself is given out. These results will require further consideration. At present I am inclined to think the pungent gas is one atom of nitrous and one of oxygen or what I formerly con- sidered as nitric acid. (See Vol. 1, plate 4, ng. 27.)
Some authors have found as they conceive, other oxides of iron, containing less or more of oxygen than the above ; thus Darso finds by calcination from 15 to 56 oxygen on 100, (Nicholson's Journ. Vol. 17); but there is great reason to believe that uncertainties must exist in his mode of experimenting sufficient to account for the anomalies observed. This author has suggested some doubt whether the oxygenous gas naturally contained in water has any effect on the salts with green oxide of iron. I have ascertained that point by re-
METALLIC OXIDES. 33
peated experiments, and can assert that the oxygen in water immediately unites to the green oxide of iron to convert it into red, and that the green sulphate may be used as an ac- curate test of the quantity of oxygen in water. When pure green sulphate of iroh is dropped into water and then the oxide precipitated by a gradual addition of lime water, it falls down yellow in proportion to the oxygen in the wa- ter, which may be increased 3 or 4 times by artificial impregnation. If the oxygen of the water be previously saturated with nitrous gas, then the oxide is wholly precipitated green.
Gay Lussac, in the 80th Vol. of the AnnaL de Chimie, asserts that an oxide of iron con- taining 37.8 oxygen upon 100 iron is always obtained when iron is burned in oxygenous gas, and still more effectually when iron is oxydized by water or steam. If this oxide exist in the proportions stated, it must be a compound of 1 atom of the protoxide and 2 of the red oxide, which would give 37.3 oxygen on 100 of iron.
From the above facts and observations it is evident the atom of iron must be considered as weighing 25, (and not 50 as already given, Vol. 1, page 258) ; the protoxide is 32, and
VOL. II, E
34 METALLIC OXIDES.
the intermediate or red oxide is 2 atoms prot- oxide and 1 of oxygen = 71.
11. Oxides of Nickel.
1. Protoxide. It appears to be ascertained from the experiments of Proust (Journ. de Physiq.63— 442),Xtichter (Nichols .Jour.12.), Tupputi (An. de Chimie 78.), and RolhofF (An. of Philos. 3 — 335.), that the protoxide of nickel consists of 100 metal and from 25 to 28 oxygen. My experiments on the solution of nickel in nitric acid give me 14 grains ni- trous gas, corresponding to 12 oxygen, in the solution of 44 grains of nickel ; this gives 100 nickel to 27 oxygen, which I adopt as agreeing with the mean of the beforemen- tioned results. This oxide may be obtained by precipitation from a solution of nitrate of nickel ; it is at first white, being then a hy- drate ; when dried in a moderate temperature it becomes yellowish; after this, being heated to a cherry red, it loses from 20 to 24 per cent, of water and becomes of an ash grey colour : this is the only oxide of nickel soluble in acids, and must therefore be deemed the prot- oxide ; hence we have 27 : 100 :: 7 : 26, nearly,
METALLIC OXIDES. 35
for the weight of an atom of nickel; and not 25 or 50, as estimated at page 258. Vol. I. Intermediate oxide. Thenard discovered a second oxide of nickel by passing oxymuri- atic acid through a solution of nickel and then precipitating; it is a black powder; when treated with sulphuric or nitric acid it gives out gas, being the excess of oxygen above the protoxide ; but with muriatic acid it gives oxymuriatic acid gas. RolhofF was induced to believe, but I do not know upon what evi- dence, that this oxide contained 1^- or If times the oxygen of the protoxide. By means of oxy muriate of lime I find the prot- oxide recently precipitated, takes half as much oxygen as it had previously, to form the black oxide; and that it cannot be formed, like the red oxide of iron, by agitation with water mixed with common air. The white oxide treated with oxymuriate of lime becomes al- most instantly blue, growing darker till it gradually passes into brown, and finally black in about half an hour. It contains 40 oxygen on 100 nickel, and is most probably consti- tuted of 1 atom of oxygen holding 2 of protoxide together, more especially as it is not found in combination with acids. The me- thod I prefer to procure the black oxide is to precipitate a known weight of oxide by lime
36 . METALLIC OXIDES.
*
water ; then pouring off the clear liquid, I put as much liquid oxymuriate of lime to the moist hydrate as contains XV of the weight of the oxide of oxygen, and stir frequently for half an hour ; the point of saturation is found when more oxide put to the clear liquid is not discoloured on one hand, and when more oxymuriate of lime does not affect the colour, but remains in the clear liquid on the other hand.
12. Oxides of Tin.
There are two .oxides of tin, which have been carefully investigated by several che- mists, and appear to be ascertained with great precision. The protoxide is grey, and con- tains 13| oxygen on 100 tin; the deutoxide is white, and contains 27 oxygen on 100 tin.
1. Protoxide. There are t\v.o methods of obtaining the constitution of this oxide. The first is by dissolving a certain weight of tin filings in muriatic acid, precipitating by lime water or carbonated alkalies and drying the oxide in a moderate heat ; this is liable to some uncertainty ; the precipitate being a hy- drate, requires to be exposed to heat to expel the water ; but if the heat approaches to red, the oxide takes fire and is converted into the
METALLIC OXIDES. 37
deutoxide. The second method is to dissolve tin in muriatic acid and carefully collect the hydrogen gas evolved; this was first done by Mr. Cavendish, with his usual accuracy, and published in 1766; he found 1 oz. of tin yield 202 oz. measures of hydrogen gas. I have frequently tried this experiment and al- ways found a proportional quantity, or very nearly 200 measures for each grain of tin. This mode of investigation appears to me unexceptionable. Now 200 hydrogen unite to 100 oxygen, and 100 grain measures of oxygen=.134 grain in weight; hence if .134 oxy. : 1 tin :: 7 oxy. : 52 nearly for the weight of an atom of tin, on the presumption this is the protoxide.
2. Deutoxide. This may be obtained by heating tin till it takes fire, and the produce of the combustion is the oxide required; but to ascertain the proportions of tin and oxygen two other methods are preferable ; the one is to treat tin with nitric acid of the sp. gr. 1.2 to 1.4; a violent effervescence and great heat ensue and the tin is converted into a white powder. This being dried in 100* gives about 160 grains for 100 of tin. It consists of the deutoxide united to a little acid and water; these two may be driven off by a low red heat, and 127 grains of the deutoxide
38 METALLIC OXIDES.
remain in the state of a white powder. The other method is to treat a solution of the prot- oxide of tin with oxy muriate of lime till it is saturated; this will be found when 59 grains of the protoxide have acquired 7 grains of oxygen, or 1 13{ have acquired 1.3 J of oxy- gen, which corroborates the result by the 1st method. This oxide containing just twice as much oxygen as the former, may justly be con- sidered as the deutoxide. No higher oxide of tin has been obtained.
The two oxides, though both white when precipitated, may be distinguished from their different appearances ; the first is curdy, the second, gelatinous.
It may be proper to subjoin authorities for these oxides:
Tin Protoxide Deutoxide Cavendish, from the hydrogen 100 113.5
Proust (Journ.de Physique 59—341) 100 115 127^.128*
Gay Lussac (Annal. de Chimie 80—170) 100 113.5 127.2f
Berzelius(Annal.deChim. 87— 55) 100 113.6 127.2$
My own, as above 100 113.4 127
* By nitric acid, the result of 3 experiments all agreeing for the deutoxide ; the protoxide is by calculation and less certain. He afterwards adopts 13.6 from Berzelius. Journ. de Phys. Aug. 1814.
f The protoxide from hydrogen by solution; the deut- oxide by transmitting steam over the metal at a red heat.
t The 2d. by oxydizing the sulphuret of tin by nitric acid; the 1st. by inference only, one half of the oxygen of the 2d.
METALLIC OXIDES. 39
13. Oxides of Lead.
There are three oxides of lead now gene- rally recognized, the yellow, the red, and the brown, the proportion of oxygen in each of which has been investigated by several chemists whose results do not well accord with each other. I shall treat of them under the following names, namely the protoxide, the intermediate oxides, and the deutoxide, for reasons which will appear,
1. Protoxide. The yellow oxide of lead is the only one capable of forming salts with acids. Lavoisier found the oxygen of this oxide combined with 100 lead to be 4.47 j Wenzel, 10; Proust, 9; Thomson, 10.5; Bucholz, 8; Berzelius, 7.7. This last ac- cords best with my own experience ; but it is chiefly from the other combinations of lead, that the weight of its atom as well as that of the protoxide are determined and confirmed, as lead forms several very definite compounds with acids, &c. The quantity of oxygen in the protoxide may be found by several me- thods, as under.
1st. By dissolving a given portion of the oxide in acetic acid, and precipitating the lead by another metal, as zinc; in this case
40 METALLIC OXIDES.
the oxygen of the lead goes to the zinc which becomes dissolved, and from the loss of weight of the zinc and the proportion of oxygen in zinc oxide being previously known, and the weight of the precipitated lead being found, we have data for determining the ox- ide of lead. I took 200 measures of acetate of lead solution (1.142), which I knew con- tained 27 grains of oxide of lead ; this being diluted with an equal volume of water, the lead was precipitated by a rod of zinc ; in 6 hours an arbor saturni was formed which was collected and well dried; it weighed 21 f grains, and the zinc rod had lost 7 grains : cafe must be taken in performing this expe- riment that all the lead be not precipitated, otherwise the oxide of zinc begins to fall, and the result is uncertain. In the residuary liquid I got 4 grains of sulphate of lead by sulphuric acid. Here then we have the oxy- gen of 21 1 lead transferred to 7 zinc; but if 7:21f ::29:90 nearly. Now it is known that 29 parts of zinc take 7 of oxygen, there- fore 90 lead take 7 of oxygen, and the atom of lead=90, and the protoxide 97.
I formerly stated the atom of lead 95. Vol. 1, page 260.
2. By dissolving 180 grains of lead in ni- tric acid in a small thin capsule, and heating
METALLIC OXIDES. 41
it till the salt was quite dry, I got 288 grains of salt, weighed in the capsule; 36 grains of this salt yielded 24J yellow oxide by a low red heat=22§ lead. This gives 90 lead to 7 oxygen.
3d. Again, 36 grains of the above salt, dissolved in water, precipitated by ammonia, and well washed on a filter, gave 23 4* grains of oxide separated from the filter, and this had acquired 1 grain, making 24 + grains of oxide from the 22 f lead as before ; the resi- due of liquid gave no signs of lead by hydro- sulphuret of ammonia. The same quantity of salt precipitated by an excess of lime wa- ter gave only 22 grains of oxide ; but hydro- sulphuret of ammonia precipitated 2 4. grains of sulphuret of lead from the clear liquid.
II. Intermediate oxide or oxides. Minium or red lead, &c. Minium is an article of commerce used as a pigment and for various other purposes. It is made by exposing the yellow or protoxide of lead finely pulverized to a low red heat in a current of air, and con- stantly stirring the oxide so as to expose fresh particles to the air. In two days the yellow oxide is converted into the red. Several au- thors observe that red lead usually contains 1,2, or more grains per cent, of impurities insoluble in nitric and acetic acids; the spe-
VOL. II. F
42 METALLIC OXIDES.
cimen I used however was so pure as not to leave more than 4- of a grain per cent, of insoluble matter after being heated red and treated with dilute nitric acid.
Some of the most remarkable properties of red lead are, 1st. It is never obtained in combination with any acid; 2d. It yields oxygen gas when exposed to a bright red heat or when treated with concentrated sulphuric acid, and is in both cases reduced to the pro- toxide; 3d. When treated with dilute nitric acid it is dissolved in part, but constantly leaves an insoluble brown residuum, which is the deutoxide, as will be shewn; the weight of the deutoxide obtained is by my experi- ments 20 per cent, and the part in solution is found to be the protoxide; 4th. When treated with muriatic acid, muriate of lead is formed and, oxy muriatic acid given out; 5th. When treated with dilute acetic acid or cold con- centrated acetic acid, \ of the oxide is dis- solved and the remainder is still red, its co- lour being rather improved; if concentrated acid be used and boiling heat applied, then 4. of the whole oxide ia dissolved and ~ re- mains of brown oxide, the same as with ni- tric acid.
Some of the above facts are new, and may contribute to elucidate this most curious
METALLIC OXIDES. 43
oxide, which scarcelyhas a parallel. Proust is the only author I know who has given a plausible conjecture concerning the peculiar nature of this oxide. He supposes it a com- pound of the yellow and brown oxides. This I believe is the fact ; but it will be found I apprehend to be a compound of 1. atom of oxygen with 6 of the yellow oxide, as will appear from what follows.
Respecting the quantity of oxygen in the red oxide, Lavoisier finds 9 oxygen to 100 lead, Thomson 13.6, and Berzelius 11.55. This last is partly from experience and partly from a supposed analogy, that the successive oxides of the same metal contain oxygen as 1, If and 2 respectively ; and having found (I believe) correctly, that the brown oxide contains just twice as much oxygen as the yellow, this ingenious and generally accurate author adopts the theoretic inference in this in- stance at least prematurely, and concludes the red oxide is the mean between the yellow and the brown. But we must appeal to ex- perience.
It has already been stated that when red lead is exposed to heat, oxygen gas is given out, and it may be added, a small trace of water; and yellow oxide remains.
44 METALLIC OXIDES.
This experiment requires considerable skill. If too great a heat is used, a part of the lead is reduced or revived as it is termed; if too little heat, then a part of the red lead remains unaltered. In performing this expe- riment I use a small clean iron spoon to hold the red lead, and cover it by another iron spoon ; the whole is then held by a pair of tongs in a red fire till the spoon exhibits a uniform moderate red, and some time after.
It is then withdrawn and cooled, and the oxide weighed. The average loss of weight is nearly 2 grains per cent. If only 1 grain or less, a considerable portion of red oxide remains mixed with the yellow; if 3 or more grains, then the margin of the oxide exhi- bits particles of lead amounting to TV> less or more, of the original weight; this can be easily separated from the oxide if necessary, but it is apt to adhere to the iron ; when red oxide remains, it is so mixed with the yellow as not easily to be separated, but its quantity may be determined by nitric acid, which dis- solves the yellow, and £ of the red, leaving a residuum of brown oxide, from which the quantity of red is inferred. Now if the loss of weight of 100 red oxide be only 2 grains, and a part of that be water, it is impossible
METALLIC OXIDES. 45
that 115.55 should lose 3.85 grains of oxygen, according to Berzelius. Another experiment, equally decisive of the question, is to deter- mine the quantity of oxygenous gas to be ob- tained by heat or acids from a given weight of red lead. In one experiment made with great care, 500 grains of red oxide gave 6 grains of oxygenous gas by sulphuric acid; in another, 200 yielded 2 J grains. In order to vary the mode of determining the quantity of oxygen, into 210 measures of test green sulphate of iron solution, (1 .156) = 16.8 green oxide, put 160 grains of minium; to this was added dilute muriatic acid more than sufficient for the minium : The oxymuriatic acid from the oxygen of the minium was in- stantly seized by the oxide of the iron, the whole of which was found by precipitation to be changed from green to red and an ex- cess of oxymuriatic acid appeared. Now 16.8 oxide would require 1.86 oxygen to be- come red, which it must have acquired from 160 of red lead; or 100 red lead yielded 1.2 oxygen, the same proportion as by sulphuric acid. These experiments point out 1.2 oxy- gen in 100 red lead as the excess which con- verts the yellow to the red oxide. Were any doubt to remain on the subject, the ex- periment with nitric acid and red oxide will
46 METALLIC OXIDES.
remove it. If the red oxide contained a mean of oxygen between the yellow and the brown, when it is treated with nitric acid more than 50 per cent, of brown oxide would be ob- tained instead' of 20, which is contrary to all experience. It must be observed that Berzelius informs us he extracted the yellow oxide, mechanically mixed (as he conceives) with the red oxide, by digestion with dilute acetic acid; but he does not inform us how much per cent, his minium was reduced by this operation. From what is stated above, it appears that about J- of the whole is thus dissolved. The remaining half would then contain double the quantity of oxygen and brown oxide per cent, that the original did. Still these quantities are inadequate to explain the phenomena. Besides it cannot be admitted that a red and a yellow powder can be inti- mately mixed in equal quantities and the mixture not be distinguishable without diffi- culty from the red one, and be altogether dif- ferent from the yellow. We must then con- clude that the minium of commerce (such as I have used) is a true chemical compound.
Grounding our reasonings upon the preced- ing facts, there are but two suppositions that can be considered as plausible, respecting the constitution of the red oxide. It may be 1
METALLIC OXIDES. 47
atom of oxygen and 5 of yellow oxide, or I atom of oxygen and 6 of yellow oxide. The former would give 1.4 per cent, extra oxygen in 100 red oxide, and 21 brown oxide; the latter would give 1.2 per cent, extra oxygen and 18 brown oxide. I adopt the latter sup- position ; because it agrees with experiment in regard to oxygen, and gives the brown ox- ide a little lower than experiment, as may be expected on two accounts; first, the residue of brown oxide contains the insoluble dross of the red oxide (which was very small however, as stated above) ; and, second, unless a con- siderable excess of nitric acid be used, or long digestion, a small portion of the red oxide es- capes decomposition. Another and still more important consideration, as to the question whether 5 or 6 atoms, is the equal division of the red oxide by the operation of cold acetic acid; it reduces the 1 oxygen and 6 yellow oxide to 1 and 3 atoms; whereas if we adopt the other, we must conclude it reduces the 1 and 5 to 1 and 2|, a position that cannot well be reconciled to the atomic theory.
According to this conclusion then the red oxide of lead or minium of commerce is con- stituted of 1 atom of oxygen holding 6 atoms of yellow oxide together; or it is composed of 100 lead and 9.07 oxygen. When it is
48 METALLIC OXIDES.
digested in cold acetic acid the residuum con- stitutes another oxide consisting of 1 atom of oxygen and 3 of yellow oxide, or 100 lead and 10.4 oxygen, possessing the same colour as the former, but distinguishable by its not being acted on by cold acetic acid, and by its containing twice as much brown oxide and extra oxygen as minium. No doubt the other intermediate oxides of 1 to 4 and 1 to 5 exist, and are all alike red; but have not perhaps any remarkable distinctions besides their containing different proportions of oxygen and brown oxide. Whether an oxide consist- ing of 1 oxygen and 2 yellow oxide exists, I have not discovered; but that 1 oxygen and 1 yellow oxide are found united, appears below.
III. Deutoxide. This is the flea-brown ox- ide mentioned above. It may also be obtained by treating solutions of salts containing the yellow oxide by oxymuriate of lime, in which case the oxide is precipitated, leaving the acid in the liquor, a proof that it is inso- luble in acids. Its more remarkable proper- ties are : 1st. like the red oxide, when heated to a low red, or treated with sulphuric acid, it yields oxygenous gas, and more copiously; it is thus reduced to the yellow oxide: 2d. with muriatic acid it yields oxymuriatic acid
METALLIC OXIDES. 49
in great plenty and muriate of lead : 3d. it detonates when rubbed with sulphur in a mortar.
The quantity of oxygen in the brown ox- ide is stated by Thomson at 25 oxygen to 100 lead, by Berzelius at 15.6 to 100. This last is very nearly right by my experience, and being just double of the oxygen in the prot- oxide, it warrants us in denominating it the deutoxide. Berzelius finds 100 of the brown oxide lose 6.5 by a red heat so as to reduce it to the yellow; Dr. Thomson finds the loss 9 grains. This difference is easily accounted for; it loses, I find, from 7 to 10 grains per cent, according to the previous degree of dryness ; when exposed to a moist atmosphere it attracts humidity; when dried in a tempe- rature of 200° and exposed to red heat imme- diately after, it does not lose more than 6.5 or 7 per cent. This is corroborated too by the oxygen expelled by sulphuric acid. From 100 grains of brown oxide and sulphuric acid in a gas bottle, I obtained by the heat of a lamp 8.3 oz. of oxygenous gas = 5.3 grains; about 120 grains of grey sulphate of lead were left in the bottle. The oxygen is rather less than was expected; but it must be re- membered that 100 grains of brown oxide, obtained in the ordinary Way, have the inso-
YOL. II. O
50 METALLIC OXIDES.
luble dross of 500 red oxide in them, which must have some influence in diminishing the production of oxygen.
Though the above might be deemed suffici- ent to demonstrate the proportion of oxygen in the brown oxide, I was desirous to corro- borate the results by oxy muriate of lime. I found repeatedly that 100 grain measures of acetate of lead (1.142) = 13.8 yellow oxide, required 400 measures of oxy muriate of lime=l oxygen, to precipitate the whole of the oxide in a brown state. Now if 13.8 : 1 :: 97:7. Again, into 240 measures of test green sulphate of iron (1.156) = 19 oxide, were put 40 grains of brown oxide of lead, together with a sufficient quantity of muria- tic acid to saturate the lead, and discharge the oxygen; after due agitation sulphate of lead was precipitated, and the whole of the oxide of iron was found, when precipitated, to be yellow. But 19 grains oxide of iron re- quired + of oxygen to become yellow; hence the 40 grains brown oxide of lead must have furnished 2 + grains of oxygen to form oxy- muriatic acid, which transferred it to the oxide of iron. If 40:2+ :: 100 i5+ oxygen, for the excess or secoridtioseof oxygen in 100 brown oxide, such as is obtained/by nitric acid along
" tlniii '■ ; ]r
METALLIC OXIDES. 5}
with its impurities; which agrees with the results obtained by the other methods.
14. Oxide of zinc.
When zinc is exposed to a strong heat it burns with a brilliant white flame, and a white powder sublimes, which is the oxide of the metal. When dilute sulphuric acid is poured on granulated zinc, hydrogen gas is produced in great abundance and purity; the metal is oxidized at the expence of the water and dissolved in the acid, the oxide may be precipitated by an alkali; it is white both when precipitated and dried, and when heated does not differ from that obtained by combus- tion. By a violent heat it runs into glass.
The quantity of oxygen in zinc oxide is, I think, best estimated by the hydrogen gas produced during the solution ; it may also be obtained by direct combustion, or by solution in nitric acid and calcination. Dr. Thomson determines the oxygen by comparison of the weights of real sulphuric acid and metallic zinc in a solution of sulphate of zinc, along with the consideration that the proportion of sulphuric acid and oxygen in the metallic sulphates is known ; Mr. Cavendish obtained 356 oz. measures of hydrogen from 1 oz. of
52 METALLIC OXIDES.
zinc by solution. I dissolved 49 grains of zinc in dilute sulphuric acid and obtained hy- drogen, after the rate of 363 grain measures for 1 grain of zinc = 182 measures of oxygen = .24 grain of oxygen.
The following are the principal authorities for the quantity of oxygen in zinc oxide, in the order of lime.
Zinc. Oxygen.
1766. . Cavendish 100 + 23.3
1785. Lavoisier -J- 19.6
1790—1800. Wenzel and Proust ... f- 25
1801. Desorme and Clement 1- 21.7
Davy .„. J- 21.95
Berzelius -f- 24.4
Gay Lnssac — — -j- 24.4
Thomson \- 24.42
My own — — -|- 24
Now if 24oxy. :100 zinc::7 oxy.:29zinc, nearly, which is therefore the weight of an atom of this metal, on the supposition that the oxide is 1 oxygen and 1 metal; and the atom of oxide = 36.
I formerly estimated the atom of zinc at 56 (Vol. 1, page 260). This was occasioned by taking the above as the deutoxide instead of the protoxide. By violently heating the oxide of zinc in a close vessel, Desorme and Clement reduced the oxygen nearly one half, so as to afford a presumption that an oxide
METALLIC OXIDES. 53
with half the oxygen of the common one sub- sisted. Since that time some observations of Berzelius seem to shew that a sub-oxide of zinc exists. It does not appear however, that such oxide is ever found in combination with acids; and, granting the accuracy of the ob- servations, it is rather to be presumed to be the semi-oxide, or 1 atom of oxygen and 2 of metal, than the protoxide. No higher oxi- dation of zinc than the above has yet been obtained, and probably does not exist.
15. Oxides of potassium.
Since writing' the articles "potassium and Sodium/' in the former volume, a very impor- tant essay relating chiefly to these subjects has been written by Gay Lussac and Thenard (a copy of which they were so good as to send me), entitled " Recherches Physico-chimi- ques, &c." in 2 Vol. — Many of the most in- teresting experiments of Davy have been re- peated on a larger scale, and a great number of original ones added; these ingenious au- thors endeavour to sum up the evidences for and against the two hypotheses concerning potassium and sodium, namely, as to their be- ing metals or hydrurets, and upon the whole incline to the former, allowing however, that
54 METALLIC OXIDES.
the facts afford great plausibility to both. One thing they seem to have discovered and established, that the new bodies or metals ad- mit of various degrees of oxidation, and of course these products have a claim to be classed amongst oxides in general though the nature of their bases may still be an object of dispute.
They find three oxides of potassium ; the lowest degree is obtained by exposing potas- sium to atmospheric air in a small bottle, with a common cork; a gradual oxidation takes place; a blueish grey brittle product is ob- tained; there does not appear however, to be any proper limit to this oxidation besides that which they admit as characterizing the second degree or potash, which degree of oxidation may always be immediately obtained by plac- ing potassium in contact with water. This I think should be called the protoxide and con- sidered as 1 atom of potassium, and 1 of oxygen ; before this point it is potassium and pot-ash mixed or perhaps combined.
Besides these there is another obtained by burning potassium in oxygen gas at an eleva- ted temperature; this oxide is yellow* fusible byjheat, and crystallizes in lamina on coolings it contains three times as much oxygen as pot- ash ; put into water it is suddenly decomposed*
METALLIC OXIDES. 55
giving out 4. of the oxygen in gas and becom- ing potash. Very probably an oxide contain- ing twice as much oxygen as potash might be formed with some mark of discrimination, by uniting 18 parts potassium with 56 of yel- low oxide, but this has not vet been done.
According to these conclusions the weights of the oxides of potassium may be stated as under.-— Potassium 35, protoxide or potash 42, deutoxide (supposed to exist) 49, and the yellow or tritoxide 56. Hence we have
Potassium. Oxygen.
Protoxide (potash) 100 -f- 20 7 Gay Lussac & Thenard
19 j Davy
Deutoxide 100 + 40 (unknown)
Tritoxide 100 + 60 Gay Lussac & Thenard
One feels unwilling to admit of a tritoxide, (and that perhaps the only one existing,) when the deutoxide is unknown, were it not upon good authority. The obscurity on this subject may be removed by future expe- riments.
It may be proper to add that Gay Lussac and Thenard concur with Davy in assigning a much greater saturating power to potassium and sodium than to the fused hydrates of pot- ash and soda of equal weights. From the ta- ble, Recherches, Tom. 2, p. 214, it may be deduced that 35 potassium require as much
56 METALLIC OXIDES.
sulphuric acid to saturate them as 50 or more of the hydrate of potash; and that 21 sodium are equivalent to 36 or 37 hydrate of sodium. If these results are accurate, the weights of potassium and sodium, considered as hydru- rets, cannot be as we have deduced them at pages 486 and 503, Vol. 1, namely, 43 and 29 respectively, but 35 and 21, as at page 262.
16. Oxides of sodium.
Gay Lussac and Thenard find a suboxide of sodium in the same way as that of potas- sium, and it is probably a compound of soda and sodium : the remarkable oxidation which produces soda is, I should imagine, the prot- oxide or one atom to one, as obtained by placing sodium in contact with water. A higher oxide is obtained as with potassium, by burning sodium in oxygen gas with a vi- vid heat. It resembles the yellow oxide of potassium in its appearance and properties. The degree of oxidation varies in the differ- ent experiments from 1^ to l.-|- times the oxygen of soda. It is probably a combina- tion of the protoxide and deutoxide. Hence the oxides of sodium may be as under; reck- oning the atom of sodium 21, and soda 28.
METALLIC OXIDES. 57
Sodium. Oxygea. Protoxide (Soda) 100 + 33*
Intermediate oxide 100 -j- ^0
17. Oxide of bismuth.
Only one oxide of bismuth is known, and the proportion of its parts has been gradu- ally approximated by Bergman, Lavoisier, Klaproth, Proust, and others. Berzelius mentions a purple oxide obtained by exposing bismuth to the action of the atmosphere; but as no experiments have been made upon it, we cannot adopt it at present. According to Klaproth and Proust, 100 bismuth unite with 12 oxygen; but by the more recent ex- periments of Mr. J. Davy and Lagerhjelm 100 bismuth take 11.1 or 11.3 oxygen. If we adopt this last, which is doubtless near the truth; we shall have 11.3: 100:: 7:62 for the weight of the atom of bismuth, on the supposition that the compound is the protox- ide or 1 atom of metal to 1 of oxygen. My former weight of bismuth was 68 (page 263), which is clearly too high.
Bismuth is best oxidized by nitric acid. Part of the oxide combines with the acid and part precipitates in the state of a white pow- der; if the whole be gradually heated, the acid
VOL. n. H
58 METALLIC OXIDES.
is driven off, and at a low red the oxide re- mains pure; it is fused into glass and of a red or yellow colour, according to the heat em- ployed. Bismuth may also be oxidized by heat in open vessels ; yellow fumes arise which may be condensed and are found to be the oxide.
18. Oxides of antimony.
Considerable difference of opinions exists with regard to the oxides of antimony. Proust finds two oxides which he determines to consist, the first, of 100 metal + 22 or 23 oxygen ; the second of 100 metal + 30 oxygen. Thenard finds 6 oxides: J.Davy two oxides, namely, 100 metal + 17.7 oxy- gen, and 100 4- 30 oxygen. Berzelius infers from his experiments that there are 4 oxides of antimony, the first containing 4.65 oxy- gen, the second 18.6, the third 27.9, and the fourth 37.2 of oxygen on 100 metal. He ad- mits however that the oxide obtained by boil- ing nitric acid on antimony and expelling the superfluous acid by a low red heat, consists of 100 metal -I- 29 to 31 oxygen, as determined by Proust and others. This is certainly the most definite of the oxides, next to that which is obtained from the solution of antimony in
METALLIC OXIDES. 59
muriatic acid. This last may be had by pouring water into a solution of muriate of antimony ; a white powder precipitates, which is the oxide with a little muriatic acid ; the acid may be abstracted by boiling the preci- pitate in a solution of carbonate of potash. This oxide is a grey powder, and fusible at a low red heat. It enters exclusively into va- rious well known compounds, as the golden sulphur of antimony, antimoniated tartrate of potash, &c. Its constitution, according to Proust, is 100 metal + 23 oxygen ; but J. Da- vy finds only 17.7 oxygen, andBerzeliiis 18.6. As this oxide possesses the most distinct fea- tures, and besides is the most important; it is desirable its constitution should be ascertained without doubt. From several experiments I made on the precipitation of antimony by zinc, I conclude the oxide contains about 18 oxygen on 100 metal. I took the common muriate of antimony with excess of acid, and immersed a rod of zinc into it, covering the whole with a graduated bell glass. Hydrogen gas was produced by the excess of acid, and its quantity was ascertained; the antimony was in due time precipitated, and when the operation ceased, the loss of zinc and the weight of antimony were found. For in- stance, to 50 measures of 1.69 mur. ant. 60
60 METALLIC OXIDES.
water were added, no precipitation was ob- served; a zinc rod was put in and the whole covered by a bell glass, over water; in a few hours the operation had ceased, and there appeared 3480 grain measures of hydrogen gas generated ; the dried antimony weighed 25f grains, and the zinc had lost 29 grains. Now 3480 hydrogen require 1740 of oxygen = 2.3 grains in weight. But 29 zinc require 7 oxygen; therefore the zinc must have got 4.7 oxygen from the antimony; that is, 25.5 antimony; were found united to 4.7 oxygen; this gives 100 antimony +18*4 oxygen. I conclude then that the error is with Proust; and this appears to be confirmed by the con- sideration that Proust himself obtains only 86 oxide of antimony from 100 sulphuret, which he allows to contain 74 antimony; now if 74: 12 :: 100: 17 nearly. I am therefore inclined tp adopt 18 for the oxygen which combines with 100 antimony to form the grey oxide. Whether this is the protoxide or deutoxide may be disputed; and the facts known con- cerning the other oxide or oxides will scarcely determine the case : but the : proportions of the muriate and sulphuret of antimony accord imjch better with the former supposition. Now if; 18:100 ;7: 39, for the weight of the atom; of antimony ; I prefer the weight 40,
METALLIC OXIDES. 61
deduced from the sulphuret, as announced in Vol. 1, page 264.
The oxide which contains 30 on 100 must be 2 atoms of the deutoxide and 1 of the protoxide united. What Berzelius calls the white oxide or antimonious acid, may be 1 atom of each oxide united, containing 27 oxygen on the 100. The oxide supposed to contain 36 or 37 oxygen on 100, and which must be considered as the deutoxide, has not been proved to exist separately. My efforts to procure it have failed as well as those before mine : by treating muriate of antimony with oxymuriate of lime I have obtained oxides of 30 on the 100, but never much higher. Whenever a greater proportion of oxymuri- ate of lime is added, the smell of the gas be- comes permanent.
Antimony exposed to a red beat in a current of common air or oxygenous gas takes fire, and white fumes arise formerly called flowers of antimony \ this oxide contains 27. or 30 oxygen on 100 metal.
Antimony thrown into red hot nitre is oxi- dized rapidly ; the remaining powder, washed in water, is found to be a compound of oxide of antimony and potash. Berzelius calls the oxide the antimonic acid, and the salt the antimoniate of potash. It consists, according
62 METALLIC OXIDES.
to his experience, of 100 acid and 26.5 pot- ash. A similar salt formed between the anjti- monious acid and potash is constituted of 100 acid and 30.5 potash.
19. Oxide of tellurium.
We are chiefly indebted to Berzelius for the proportions in which tellurium combines. He finds 100 tellurium unite to 24.8 oxygen. Also that 201.5 tellurate of lead gave 157 sulphate of lead. This last contains 116 ox- ide of lead, which must therefore have com- bined with 85.5 of the oxide of tellurium. Hence 97 oxide of lead would combine with 71.5 oxide of tellurium = 57§ tellurium +14 oxygen. Whether this oxide of tellurium is the protoxide or deutoxide, is somewhat un- certain. The atom of tellurium will weigh 57 1 in the latter case, but only 28 or 29 in the former. The analogy of the oxide to acids favours the notion of a deutoxide; but the facility with which the tellurium is volatilized by hydrogen is in favour of the lighter atom. The oxide is a white powder; it is produced by dissolving the metal in nitro-muriatic acid and precipitating by an alkali.
METALLIC OXIDES. 63
20. Oxides of arsenic.
There are two distinct combinations of ar- senic and oxygen; the one has been long* known as an article of commerce under the name of arsenic. It is a white, brittle, glassy substance, obtained during the extraction of certain metals from their ores. Its specific gravity is about 3.7. According to Klaproth boiling water dissolves from 7 to 8 per cent, of the oxide of arsenic; but on cooling it retains only about 3 per cent.; and this I find is gradually deposited on the sides of the ves- sel till it is reduced to 2 per cent, or less in cold weather, and by some months standing. Water of 60° degrees or under dissolves no more than J per cent, of the oxide. At the temperature of about 400° the oxide sublimes* This oxide combines with the alkalies, earths, and metallic oxides somewhat as the acids do, but does not neutralize them, and in other respects it is destitute of acid properties; as for instance, it does not affect the colour tests. It is extremely poisonous.
The other oxide is obtained by treating either the white oxide or pure metallic arsenic with nitric acid and heat. One hundred grains of white oxide require two or three times their weight of nitric acid, of 1.3, to
64 METALLIC OXIDES.
oxidize them. The new oxide is produced in a liquid form ; from which the excess of nitric acid may be driven by a low red heat, and the oxide is obtained pure in the form of a white opake glass, which soon becomes li- quid by attracting moisture from the atmo- sphere. This oxide, discovered by Scheele, has all the properties of acids in general, aud is therefore denominated arsenic acid. When just fluid by attracting moisture it has the sp. gravity 1.65 nearly. It is represented as equally poisonous with the white oxide.
The proportions of the elements in these two oxides have been investigated with con- siderable success. Proust finds the white oxide constituted of 100 metal and 33 or 34 oxygen, and the second of 100 metal with 53 or 54 oxygen: with these results those of Rose and Bucholz nearly agree. Thenard finds 100 +34.6 for the white oxide, and 100 + 56.25 for the acid: and Thomson 100+52.4 for the acid. Eerzelius however, infers from his recent experiments that the oxide consists of 100 metal +43.6 oxygen, and the acid of 100+71.3; these last results I have little doubt are incorrect from my own experience.
It appears that when arsenic is oxidized by nitric acid, 100 parts yield from 152 to 156 of acid, dried in a low red heat. The differ-
METALLIC OXIDES. 65
ences may in part be owing to the metal being partly oxidized at the commencement of the operation. On this account I should suppose 55 or 56 to be the proper quantity of oxygen united to 100 metal to form the acid. Proust and Thenard both found that 100 white oxide, when converted into acid by nitric acid¥ gave 115 or 116. I have found the same., ) Now if 116: 100:: 156: 134 ; hence the white ox- ide of arsenic must contain 100 metal to 34 oxygen, if the data be correct; or the metal and oxygen are as 3 to 1 nearly. It is highly improbable that any inferior oxide subsists, as no traces of such have been found, if we disallow a conjecture of Berzelius on the subject. The white oxide of arsenic must then be considered as the protoxide, and the atom of arsenic must weigh 21 nearly, and that of the protoxide 28.
It i$ plain the other is not the deutox- ide, as it does not contain twice the, oxygen of the protoxide; but as the proportion of oxygen in it is to that of the protoxide, as 5:3, it may be a compound of 2 atoms of deutoxide, and 1 of protoxide; that is, it may be the superarseniate of arsenic, if we consider the deutoxide as the acid, and the protoxide as the base. According to this view, the compound oxide, or arsenic acid of
VOL. II. I
66 METALLIC OXIDES.
Scheele, is constituted of two atoms of the d^utoxide, weighing 70, and 1 atom of the protoxide weighing 28, together making 98, for;the weight of an atom of arsenic acid, =6$ arsenic + 35 oxygen : and 100 arsenic take 55.5 oxygen to form the acid, agreeably to the above recited experiments. Singular as this conclusion may appear, the tr nth of it is put %&yoftd dotibt^ I think, by the follow- ing experiments.
I have repeatedly found that 28 parts of white ox itle in solution are sufficient to throw down-84 parts of lime, from lime-water, so as to produce' 52; parts of arsenite of lihle, and leaVd'the^te^ free from both elements. 1Fft& cotoftritts the riotiou of the atom of prot- oxide w^igh^ s
bt(M to 24pairts of lime dissolved -in > water we put 98 parts of dry arsenic acid, 'the com- pound < remains in soldtion, and is perfectly neutral to the colour test^ but so that the addi- tion of !&( Ismail quantity of either ingredient disturbs the -neutrality.' If to this solution 24 parts Of lime dissolved in water be added, the compound remains a limpid solutiou; f but is very< limy to the test. If to this we putin like- manner^ 24 parts more of lime, the whole compound is throwu down, and yields;, wh^n dried, 170 parts bfarseniate of lime,
METALLIC OXIDES. 67
the liquid being now free from both ele- ments. Here we see first, two atoms of the deutoxide, neutralized by two atoms of base, namely, 1 of arsenic oxide, and 1 of lime; but (second), when one atom more of lime is added, an union of 2 deutoxide, and 3 of base is effected, which of course is an alkaline salt; when (third) more of limeis add- ed, the 2 deutoxide and the 1 protoxide each attach 1 of lime, and form a still more alka- line salt, which being- insoluble, is wholly thrown down, most probably in a compound state of 98 parts arsenic acid, combined with 72 parts lime.
In like manner, I find that 42 parts of pot- ash, 28 of soda, and 12 of ammonia, seve- rally neutralize 98 parts of arsenic acid.
1st. 24 lime -f- 32.7 arsenic acid c== insoluble arseuiate
2d. : — — -j- 49 — = soluble arseniate
3d. -f- 98 — — = neutral arseniate
It is a remarkable fact, that when neutral arseniate of potash and nitrate of lead are mixed together to mutual saturation, the pre- cipitate is found to consist chiefly of arsenic acid and oxide of lead, in proportion of 1 of acid to two of oxide, (that is, 98:194, or 100 : 198) ; which does not differ much from the determination of Berzelius.
68 METALLIC OXIDES.
I find however, only one fourth of the nitric acid in the residuary liquid in a free state; which leads me to suspect that the pre- cipitate is a compound of subnitrate and ar- seniate of lead, in which the arsenic acid and lead are in due proportion, or 98 acid, to 97 oxide. This consideration may be properly resumed hereafter.
Hence we conclude, the atom of arsenic weighs 21 (and not 42, as at page 264, Vol. 1), that of the protoxide or common white arsenic, 28; and that of arsenic acid = 98, being a compound of 2 atoms of deut- oxide, and 1 of protoxide. Or,
100 Arsenic -f 33.3 oxygen = 133.3 protoxide • + 55.5 = 155.5 arsenic acid
21. Oxides of cobalt.
There are at least two oxides of cobalt, the one blue, the other black. Authors differ as to the proportions of the elements. Proust states the blue oxide to consist of 100 metal, and 19 or 20 oxygeij, and the black of 25 or 26 oxygen. Klaproth finds in the blue, 100 metal and 18 oxygen. But Rolhoff accord- ing; to Berzelius, finds 100 metal and 27.3 oxygen in the blue oxide, and 40.9 in the black. I have taken some pains to invests
METALLIC OXIDES. 69
2fate these oxides, and have been able to sa- tisfy myself in a good degree, respecting their constitution. The blue or protoxide consists of 100 metal and 19 oxygen, and the black oxide of 100 metal, and 25 or 26, very nearly as Proust determined.
Protoxide. By repeated trials 1 have found, that if 37 parts of metallic cobalt be treated with the due quantity of nitro-muriatic acid, and a heat of 150% a rapid solution takes place, and a disengagement of pure nitrous gas; this being carefully collected, it will be found to weigh 8 grains, and of course corres- ponds to 7 grains of oxygen; hence 37 co- balt, unite to 7 oxygen, to form 44 of the blue oxide; and as this is the only oxide that combines with acids, it must be considered as the most simple or protoxide, being 1 atom of metal (37), and 1 of oxygen (7). The estimation of the atom of cobalt at 50 or 60, (page 265), must therefore be corrected.
Compound oxides. When the blue oxide of cobalt is precipitated from, a solution, by an alkali or lime water, and oxymuriate of lime is gradually dropped in, the precipitate chan- ges colour rapidly; it passes from blue to green and olive, thence to a dark bottle green, and finally becomes black; oxygen gas is given out copiously when an excess of oxy-
70 METALLIC OXIDES.
muriate of lime is used. I find the addi- tional oxygen requisite to convert the blue to the black oxide is what Proust states it, namely, -f of that necessary to form the blue; hence it must be considered as a compound of 1 atom of oxygen and 3 of the protoxide. Probably the other coloured oxides are 1 to 4, 1 to 5, &c* The protoxide is blue when precipitated, but it is supposed to contain water, or to be a hydrate ; as it is dark grey when heated. The blue oxide in: a short time after precipitation being still under wa- ter, changes to a yellowish or dead-leaf co- lour; which also appears to be a hydrate qf the protoxide, as it .dissolves in acids without giving out /gas, and yields the blue oxide by an alkali* According to Proust, this hydrate contains £0 or 2 1 per cent, water. If we sup- pose the blue to be 1 atom oxide, and 1 wa- ter, the yellow hydrate may be 1 water and 2 of the proto-hydrate ; or 88 oxide, and 24 water, which will be nearly 21 per cent, water.
The black oxide gives out oxygen gas by <i red heat, and is reduced to the grey oxide : it forms oxymuriatic acid, with muriatic acid, and the protoxide remains in solution.
(See Tassaert.— An. de Chimie28; The- nard, 42; and Proust, 60.)
METALLIC OXIDES. 71
22* Oxides of manganese*
One of the oxides of manganese being a natural production, and sometimes of great purity, and the metal not being obtainable without skill and labour, it may be most con* venient to adopt the inverse method in our in- vestigations; that is, to trace out the atom of metal from its oxides.
Native oxides of manganese. Of late, I have met with excellent specimens of this oxide; they are in masses of a greyi crystalline ap- pearance, sp. gr. 4, easily pulverizable into a greasy, shining, dark grey powder. They are nearly pure oxide; but the niore common sort is blacker, and contains less or more of siliceous earth. Some specimens are very
harsh, require an iron mortar to pulverise
i • K >rrif fff» • feu
them, and contain 50 or upwards per cent, of
siliceous earth. Of the common sort when pulverized, the black inclining to blue, is ge- nerally preferable to the black inclining to brown. I have not observed any earthy car- bonates mixed with ihe oxide of manga- nese. Amongst various specimens I obtained the following analyses.
72 METALLIC OXIDES.
Oxide. sand and in*
« soluble matter.
1. Grey, crystallized oxide 100 — -
2* Pulverized black oxide, from 7 ftft 9n
a bleacher, reputed good j
3. Another specimen, in the lump 77 23
4. A light brown oxide 47 53
5. A sparry oxide, abounding with? g7 .„ flint ) black brown when pulverized )
Some of the chemical characters of the native oxide of manganese are, its giving oxygen gas by a red heat, its insolubility in nitric and sulphuric acids, and its solubility in muriatic acid, but with the accompanying circumstance pf disengaging oxymuriaiic acid.
All these facts shew that it is of the higher order of oxides, or analogous to the brown and red oxides of lead.— The muriatic acid solution abovementioned, contains an oxide of an inferior degree, which is soluble in all acids, and which is the only oxide of manga- nese that appears to be soluble in acids. If this be considered, (as it may with the great- est probability), the protoxide, then it will appear from what follows, that the common native manganese is the deutoxide, and that there is an intermediate one, which contains a mean quantity of oxygen.
METALLIC OXIDES. 73
Protoxide. This may be obtained in solu- tion with muriatic acid as above, from the native oxide. Or the black oxide may be mixed with sulphuric acid into a paste, and heated in an iron spoon to redness; the mass being lixiviated, a solution of the protoxide in sulphuric acid is obtained, generally with a slight excess of the acid; in this process heat and the presence of sulphuric acid, ex- pels the redundant oxygen of the black oxide, and reduce it to the protoxide, which hence becomes soluble. If in either of these solu- tions any oxide of iron be present, whether from the manganese, or acquired during the manipulation, it is easily discovered, and se- parated, as I have frequently found. Into any solution containing a mixture of the ox- ides of manganese, the green oxide of iron, and the red oxide of iron, let lime water be gradually poured ; the red oxide of iron will be first precipitated, next; the green oxide, and lastly the oxide of manganese, which may hence be separated from each other. Iron may also be discovered and separated by carbonate of potash, which must be dropped into the solution as long as any coloured pre- cipitate appears; as soon as it has subsided, the snow-white carbonate of manganese suc- ceeds. This white carbonate may be very
VOL. II. K
74 METALLIC OXIDES.
conveniently used for obtaining solutions of pure manganese in any of the acids.
When a solution of pure manganese is treated With lime water, or ammonia, a light buff oxide, not much differing in appearance from the yellow oxide of iron, is obtained. This oxide is soluble in all acids, when re- cently precipitated; but, such is its avidity for oxygen, with moderate agitation of the liquid it acquires oxygen and becomes brown, when it ceases to be totally soluble; if dried in the air quickly, it becomes brown and ob- tains considerable oxygen. The buff oxide recently precipitated, is probably a hydrate; for, when the white carbonate of manganese is heated gradually to red, the water and the acid are both expelled, and a, grey powder Remains; this is quite black on the surface of the mass, if exposed to the air during the process. Probably this grey powder is the ptire protoxide ; it is soluble in acids, except the black powder at the surface ; perhaps but for the oxygen of the air, the protoxide would be nearly white.
From its combinations with sulphuric and carbonic acids, I find the weight of an atom of the protoxide to be 32, or the same as that of iron. Dr. John, a German chemist, who seems to have investigated these salts with
. ■
METALLIC OXIDES. 75
more attention than any other person, has de- duced nearly the same results. (Annals of Philos. 2—172). He finds 33^- sulphuric acid 4*31 oxide, and 34.2 carbonic acid +55.8 oxide; that is, when reduced to compare with my results, 34 sulphuric acid + 31.3 oxide, and 19.4 carbonic acid + 32 oxide. This near agreement may be considered as a confirma- tion of the accuracy of both. Dr. John finds, as I have done, three distinct oxides of man- ganese, the greyish green, the brown, and the black. The first of these is the only one that combines with acids ; but we differ mate- rially as to the quantity of oxygen in each. He found manganese decompose water at the ordinary temperature ; by oxidizing the me- tal this way, 100 metal acquired 15 oxygen to constitute the protoxide; according to this, 28 metal + 4 oxygen would make 32 prot- oxide; but this conclusion would be so con- trary to all analogy, that it cannot be admit- ted as satisfactory. The probability is, that the manganese must have contained a little oxygen at the commencement of the experi- ment. The general analogy of manganese to iron, lead, &c. requires that 32 protoxide should contain 7 oxygen. If this be allowed, we have the atom of manganese = 25, and not 40, (as at page 266, Vol. I), the same as
76 METALLIC OXIDES.
that of iron : and this conclusion is corrobo- rated by what follows.
2. Intermediate or olive brown oxide. This may be formed by combining oxygen directly with the buff or protoxide recently precipi- tated, and still remaining in the liquor; sim- ple agitation in oxygenous gas or common air for a few minutes, is all that is requisite. Or it may be instantly formed by treating the same moist protoxide with liquid oxyttiuriate of lime. Or it may be had by exposing the purest black oxide to a bright red heat for some time, when it will lose 9 or 10 per cent, and there will remain the olive brown oxide.
To find the proportion of oxygen absorbed, I precipitated 3.2 grains of the protoxide by lime water; the liquid containing the oxide was put into a well stoppered bottle of oxygen gas; on agitation the oxide changed colour fast, from buff to brown; in a short time it absorbed 260 grain measures of gas =.35 of a grain in weight, and then ceased to absorb. In another experiment, 3.2 grains of preci- pitated protoxide/ took 100 measures of a solution of Oxymuriate of lime, containing .35 per cent, of oxygen, (that is, 1.45 oxy- muriatic &cid). Hence as 32 take 3.5, 64 m^ttake 7; \vhieh shews the brown oxide to ■ - ( ' ■■ i i ' ? • .
METALLIC OXIDES. 77
be a compound of 1 atom of oxygen, and 2 of the protoxide.
The characters of this oxide are, its olive brown colour, its insolubility in nitric and sul- phuric acids, without heat or deoxidation, and its solubility in muriatic acid after the evolu- tion of oxy muriatic acid. By long exposure to the air, it is gradually changed, in all pro- bability into the black oxide.
3. Deutoxide. In order to determine the quantity of oxygen deducible from the purest native oxide of manganese, to convert it into protoxide, I have successfully adopted the two following methods. 1st. Let 39 or 40 grains of the oxide be mixed with 60 common salt; to this add 80 grains of water, and 120 grains weight of strong sulphuric acid, in a gas bottle. The heat must be gradually raised to boiling, and the oxymuriatic acid gas may be received in a quart of lime water. This will be found sufficient to convert 800 mea- sures of test green sulphate of iron (1.156) into red ; that is, it will produce 29 grains of oxymuriatic acid, which will cause 7 grains of oxygen, to unite to the green oxide of iron. Now 100 measures of 1.156 sulphate* according to some recent experiments of mine, contain 8 grains of green oxide, (I es- timated the sp. gr. of test sulphate, heretofore
78 METALLIC OXIDES.
at 1.149); hence 800 contain 64 oxide, and these require just 7 grains of oxygen to be united to them, to form the red oxide, as has been shewn, page 34. In the above experi- ment, the 39 grains of oxide, will be found to vanish or be dissolved, if pure, and to yield 32 grains of protoxide, making up with the 7 grains of oxygen, the original weight. Hence we have 39 grains of the oxide re- solved into 32 protoxide, and 7 oxygen. If then we allow 32 protoxide, to contain 7 oxygen, it appears that 39 grains of the na- tive oxide, consists of 1 atom manganese (25), and two atoms of oxygen (14); or it is the deutoxide of the metal. 2d. A more direct and expeditious method, of transferring the oxygen from the manga- nese to the iron, is as follows: Let 39 grains of pure grey shining oxide, be mixed with 800 of test green sulphate of iron; to this mixture let 25 or 30 grain measures of strong sulphuric acid be added: after stirring the mixture for 5 minutes, the oxide of manga- nese will be completely dissolved, and, on precipitating the oxide of iron gradually, by lime water, it will be found to be wholly yeU lowor buff; shewing that 7 grains of oxygen have been transferred from the oxide of man- ganese to that of iron. — If more green suU
METALLIC OXIDES. 79
phate of iron be used, then the surplus of the oxide will be thrown down green; the order of precipitation being the yellow oxide of iron, the green oxide of iron, and lastly, the yellow or buff oxide of manganese, as has been stated. This affords an easy and elegant method of appreciating the different oxides of manganese of commerce; and it was in this mode, the valuations of the spe- cimens in the above table were made.
The proportions of the three oxides are then as under :
r ■•
Manganese Oxygen
Protoxide 100 + 28 — buff; soluble in acids.
Intermediate oxide- -f- 42 — brown ; insoluble.
Deutoxide -{- 56 — black; insoluble.
It may be proper to subjoin the results of others, who have investigated the oxides of manganese. Bergman finds 3 oxides, con- taining 100 metal + 25, 35, and 66.6 oxygen; Dr. John finds 3 oxides, containing 100 me- tal + 15, 25, and 40 oxygen: Berzelius finds 5 oxides, containing 100 metal + 7, 14, 28, 42, and 56 oxygen ; and Davy finds 2 oxides, containing 100 metal + 26.6, and 39.9 oxy- gen, respectively.
80 METALLIC OXIDES.
23, Oxides of chromium.
There appear to be at least two oxides of chromium, one or other of which is found in combj^atiqn with the oxides of lead or iron, but hithertpj so dtiffljfi sparingly that few che-; mists have had an opportunity of investigating the proportions of chrome and oxygen, in the oxides of chromium. The chief sources for information on this subject, ( are essays by Vauquelin, An. de Chimie, Vol. 25 and, 70; by Tassaert, ibid. 31; by Mussin Puschin, ibid. 32; by Godon, ibid. 53; by Laugier ibid. ,78, and by Berzelius, Annal. of Philo- sophy, 3.
The oxides of chromium, as might be sup- posed, are distinguished for the colours which they possess and impart to the compounds into which they enter. One of the oxides is green; it gives colour to the emerald. The other is yellow, dissolved in water, but deep red when crystallized, and possesses the cha- racters of an acid; it unites with alkalies, earths, and metallic oxides; it was first found in Siberia, in combination with the oxide of lead, a salt now denominated chromate of lead, of a splendid yellow colour, inclining to orange or red. Since then, the chromate
METALLIC OXIDES. 81
of iron, has been found in France, America, and Siberia, with a prospect of greater abun- dance.
In order to investigate the weight of the atom of chromic acid, it is necessary to at- tend to such of the chromates as have been carefully examined. The chromates of pot- ash, barytes, lead, iron, and mercury, are those with which we are best acquainted.
Vauquelin has given us the components of the native chromate of lead by analysis, and those of the artificial chromate by synthesis; the results do not accord very nearly : for, ac- cording to the analysis corrected by the mo- dern science,
Chromate of lead = 62 acid -j- 97 oxide
By synth. chromate of lead e= 57| 1- 97 — —
Berzelius however, has more lately given us the results of his experience, both analy- tical, and synthetical; and he finds both to give chromate of lead nearly = 44 acid 4- 97 oxide.
Chromate of barytes (Vauq.)=47.8 acid ~f- 68 barytes
Ditto (Berz.)=44 |-SS
Native chromate of iron (Vauq.)=45 acid 4-351 oxide Ditto. (Laugier)=55 h35|
VOL. II. L
82 METALLIC OXIDES.
Having* received a small portion of chro- mate of potash in solution, from a chemical friend (J. Sims), I endeavoured to satisfy myself, as far as my materials would go, as to the nature and proportions of the chro- mates. The solution was of the sp. gr. 1.061, and consequently in 100 measures contained nearly 6.7 grains of chromic acid and pot- ash, &c- — The liquid was a beautiful yellow; it was alkaline by the colour test. By the usual tests, I had reason to believe, that the solution contained as under per cent. — namely,
2.2 gr. chromic acid
2. potash
.8 uncomb. potash
1.4 carb. potash
.3 sulphate of potash
6.7
... With this liquid neutralized by nitric acidf
I formed the chromates of lead, barytes, iron,
and mercury ; and I am inclined to believe
these salts are nearly constituted as under :
Neutral chromate of potash 46 acid -f- 42 potash
of barytes 46 \- 68 barytes
— of lead 46 (- 97 oxide
— of iron 46 ) «-f- 32 oxide (black)
1 of mercury 46 p-174 oxide (black)
METALLIC OXIDES. 83
According to these results, the atom of chromic acid weighs 46; it is made 44 by the results of Berzelius, and from 45 to 62 by those of Vauquelin; I would not be under- stood to place great confidence in the above results of mine, though I am persuaded they will be found good approximations.
Is the chromic acid the deutoxide, or the tritoxideof chromium?
The determination will evidently be affec- ted by the question, how much oxygen must be abstracted from the chromic acid to reduce it to the green oxide. Vauquelin finds 46 acid to lose 6| oxygen, and Berzelius lOf , when converted into green oxide by heat. From the former of these, one would infer chrome to be 32, the green or protoxide of chrome to be 39, and the acid or deutoxide 46: from the latter, chrome = 25, protoxide = 32 (unknown), the green oxide = 1 prot- oxide and 1 deutoxide united [= 71 = 50 chrome -f 21 oxygen = (25 chrome + lOf oxy- gen) x 2= 35f x 2] the deutoxide = 39, and the tritoxide or chromic acid = 46. I have not had an opportunity to perform any expe- riment that appears to me decisive as to the accuracy of one or other of these views ; but shall make a few remarks relative to them.
84 METALLIC OXIDES.
The green oxide being- the most prominent compound next to the chromic acid, being commonly produced from it by any deoxi- dizing process, being- the lowest oxide known? and combining- with acids, is on these ac- counts entitled to the consideration of the protoxide; indeed there does not seem an in- stance where the protoxide of a metal is un- known, whilst the deutoxide and compound oxides are known. There is however, ano- ther oxide observed by Vauquelin and by Berzelius, which is obtained by heating the nitrate, or combination of nitric acid and the green oxide, to dryness and expelling the acid ; this oxide is brown, and gives oxymuriatic acid when treated with muriatic acid ; on this account it would seem to be interme- diate between the green oxide and the chro- mic acid; ^t is prohably a combination of the two, or the chr ornate of chromium. On the other view however, it must be considered as the deutoxide. What corroborates the notion of the green oxide being 39, is the fact which I have observed, of 46 parts of chromic acid combining with 64 of the green oxide of iron to form 110 of chrotnate of iron ; in this combination the oxide of iron may be said to borrow 1 atom of oxygen from the chromic
METALLIC OXIDES. 85
acid, and the compound may then be consi- dered as the union of the green oxide of chrome, and the red oxide of iron. When this precipitate is subjected to the action of muriatic acid, a green solution is obtained containing- the oxide of chrome, and red oxide of iron is precipitated, as Vauquelin has ob- served. To form the above chromate (or ra- ther subchromate) of iron, let a given portion of neutral chromate of potash be treated with green sulphate of iron, and lime-water be added, sufficient to saturate the sulphuric acid, a brown red precipitate is obtained; more sulphate and lime water must be gradu- ally added to the clear liquid till the precipi- tate become green, when the proportions will be found as above stated. This artificial compound seems a subchromate; whereas the native compound seems to be a chromate. That there is some uncertainty in decompos- ing a chromate by heat with a view to obtain the green oxide, I have reason to suspect from having decomposed 54- grains of chromate of mercury by a moderate red heat; this com- pound contained 1.1 chromic acid, and it 'yielded only .6 of green oxide, whereas it should have been .9 or .8 at least.
Upon the whole I think the evidence is in favour of the opinion that the atom of chrome
86 METALLIC OXIDES.
is 32, the green or protoxide 39, and the deutoxide or chromic acid is 46.
24. Oxides of uranium.
There appear to be two oxides of uranium from the experiments of Klaproth, Bucholz, and Vauquelin ; but the proportions of metal and oxygen have not been very nearly ascer- tained, from the great scarcity of the mine- rals containing this metal. (Vid. Bucholz, An. de Chimie, 56 — 142. Vauquelin, ibid. 68 —277; or Nicholson's Journ. 25— 69). The oxides are obtained by precipitation from so- lutions of the minerals in the nitric or muria- tic acid, the foreign substances being first se- parated.
The protoxide of uranium precipitates dark bottle green by caustic alkalies, and forms crystallizable salts with acids; the other, probably the deutoxide, precipitates orange yellow, and forms un crystallizable salts with acids; in these respects the oxides bear a near resemblance to those of iron.
Bucholz estimates the yellow oxide at 100 metal + from 25 to 32 oxygen; as it yields oxymuriatic acid when treated with muriatic, it is most likely to be the deutoxide; now if
METALLIC OXIDES. 87
we take 28 for the oxygen combined with 100 metal, the protoxide must consist of 100 me- tal + 14 oxygen, or of 50 metal + 7 oxygen, and the atom of uranium = 50. From his ac- count of the sulphate and nitrate of uranium the weight of the atom might be inferred to be double of the above or 100a These diffe- rent conclusions can only be elucidated by fu- ture experiments.
25. Oxides of molybdenum.
The latest and as it should seem most ac- curate experiments on the oxides of molybde- num were made by Bucholz. (Vid. Nichol- son's Journal, 20, p. 121). There appear to be 3 oxides or combinations of molybdenum and oxygen, namely, the brown, the blue, and the white or yellow. The two last have the character of acids, and none of them seem to form salts with acids, like oxides in general. Bucholz ascertained the above gradation, and that the white oxide or molybdic acid con- tains 4- of its weight of oxygen; (which has since been corroborated by Berzelius) ; he also found that the blue was best formed by mixing, triturating, and boiling in water 3 parts of brown oxide, and 4 of white, or one of me- tal, and two of acid ; and that it has acid
88 METALLIC OXIDES.
qualities as well as the white. Bucholz also found 3 parts of liquid ammonia of the sp. gr. .97 dissolve 1 of molybdic acid; now 3 parts; of ammonia— .186 real (Vol. 1, p. 422); and 1:. 186:: 64-: 12, the quantity of ammo- nia usually saturated by one atom of acid; and Berzelius found 100 molybdic acid saturate 155 oxide of lead, or 63 acid to 07 oxide. The native sulphuret of molybdenum (the state in which this metal is usually found) was analyzed by Bucholz and found to consist of 60 metal and 40 sulphur.
The molybdic acid may be obtained by roasting the sulphuret in a crucible and stir- ring" it frequently; the sulphur in great part escapes in the form of sulphurous acid and the metal becomes oxidated: carbonate of soda in solution may be added to the residuum as long as any effervescence is observed; mo- lybdate of soda remains in solution and the acid may be precipitated by nitric acid. The brown oxide is best obtained by heating mo- lybdate of ammonia to red; the ammonia and part of the oxygen are expelled, and the brown oxide remains.
There are two views with which the pre- ceding results may be reconciled; namely, 1st. supposing the atom of molybdenum to weigh 21 ; and 2d, by supposing it to weigh 42 or
METALLIC OXIDES. 89
twice that number. In the first case the brown oxide will weigh 24| (49) being* sup- posed 2 atoms of metal and 1 of oxygen, the blue or protoxide will weigh 28, and the white oxide or molybdic acid will weigh 63, being a compound of the protoxide and deut- oxide, molybdena or native sulphuret will then be as usual, the protosulphuret, consisting of 21 metal and 14 sulphur, or 60 metal and 40 sulphur. In the 2d. case the brown or prot- oxide will weigh 49, the blue or deutoxide 56, and the acid or tritoxide 63. The na- tive sulphuret, molybdena, must in this view be the deutosulphuret, or 42 metal and 28 sulphur.
The former of these views exhibits the ox* ides somewhat complicated, but agrees well with the sulphuret; the latter shews the oxides in a more regularirain, but does not appear so probable from the sulphuret; besides, the no- tion of a metallic tritoxide is rather singular, especially in a metal that is rarely if ever found in combination with oxygen. Upon the whole I prefer the former view ; but it must be considered as problematical only, The atom of 60 (see page 267 Vol. 1) must doubtless be erroneous.
VOL. II. M
90 METALLIC OXIDES.
26. Oxides of tungsten.
From the experiments of D'Elhuiarts, Bu- cholz* and Berzeliusf it seems very probable that the tungstic acid is composed of about 100 metal + 25 oxygen. It is a yellow pow- der of the sp. gr. 6.12, and is best obtained from the native tungstate of lime (a scarce mineral). One part tungstate of lime and four of carbonate of potash are fused together, dissolved in water, and then the tungstic acid may be precipitated by nitric acid. There is an inferior oxide that is black or dark brown ; Berzelius reduced the yellow oxide to a flea- brown colour, by sending a current of hy- drogen gas through it in a glass tube heated red hot. 100 parts of this oxide burnt be- 107 yellow oxide. Hence 100 metal must combine with about 16| or 17 oxygen to form this oxide, which is |> of that in the yellow or tungstic acid. — Upon the whole it does not seem improbable, considering the great sp. gravity of this metal, that it forms three oxides and that the acid or yellow oxide is
* An. of Philos. 6—198 fAn. of Philos. 3—244
METALLIC OXIDES 91
the 3d. Hence the atom of tungsten must be 84, that of the protoxide 91, the deutox- ide 98, and the tritoxide or tungstic acid 105. The native tungstate of lime, if pure, ac- cording to this would be 81.4 acid +18.6 lime, which is not far from Klaproth's analysis ; he having found 18.7 lime in one specimen; nor from that of Berzelius, he having found 80.4 tungstic acid and 19.4 lime in 99.8 tungstate of lime.*
There is another view however, which would accord with the experiments and per- haps will be found preferable in other res- pects; that is, to suppose the tungstic acid to be composed of 1 atom deutoxide and 1 atom protoxide united ; in this case the atom of tungsten = 42, that of the protoxide = 49, that of the deutoxide # 56, and the tungstic acid = 105 as before.
27. Oxides of titanium.
Nothing certain is known respecting the oxides of titanium. An observation of Rich- ter, quoted by Berzelius (An. of Philos. 3—251), if it could be relied upon, furnishes an important fact, namely, that a solution of
*An. of Philos. 8—237
92 METALLIC OXIDES.
muriate of titanium containing' 84.4 oxide, gave 150 muriate of silver. Now 150 muri- ate of silver contain 28 acid ; hence 28 acid must have combined with 84.4 oxide ) but if 28 : 84.4 :: 22 : 66 nearly for the weight of an atom of the oxide. This would indicate 59 for an atom of the metal.
2 8 . Oxides of columbium .
The white oxide or acid of columbium is found in combination with the oxides of iron and manganese in proportion nearly as 4 of the acid to 1 of the aggregate oxides. The two minerals, columbiteand tantalite, though yielding these substances nearly in the same proportions, are found to differ remarkably in specific gravity, the former being about 5.9 and the latter about 7.9. Dr. Wollaston concludes however, from the agreement of the white oxides extracted, that they must be the same. The white oxide of columbium is insoluble in the mineral acids; it unites with potash by fusion, and may be precipi- tated by most acids. Some of the vegeta- ble acids, the oxalic, the tartaric, and the citric dissolve the white oxide. When the alkaline solution of columbium previously neutralized by an acid is treated with infusion
METALLIC OXIDES. 93
of galls, an orange precipitate is produced which is characteristic of columbium. No- thing certain has been determined respecting the proportions of metal and oxygen; but from the great proportion of the columbic acid found with the oxides of iron and man- ganese, together with the great sp. gravity of the compound, one may pretty clearly infer the great weight of the atom of columbium. Supposing the white oxide or acid to consist of 1 atom metal 4- 3 oxygen and that the co- lumbite is formed by 1 atom of acid to 1 of oxide, we should have 128 acid 4* 32 oxide. This would give 107 for the weight of an atom of metal, and 128 for that of the tritoxide or columbic acid; but it is unnecessary to dwell upon such conjectures.
In a recent memoir of Messrs. Gahn, Berzelius, and Eggertz (An. de Chimie, Octo. 1816), it is maintained as probable that there is only one oxide of columbium or tanta- lum, and that 100 metal take 5.485 oxygen, or 121 metal take 7 oxygen. If this be cor- rect, the atom of columbium must be 121 and the protoxide 128.
(See also An. de Chimie, 43 — 271 ; Philos. Trans. 1802; Nichols. Journ. 2— 129; ibid. 3—251 ; ibid. 25—23).
94 METALLIC OXIDES.
29. Oxides of cerium.
The mineral cerite is of the sp. gr. 4.53, and constituted of 50 or 60 per cent, of oxide of cerium, with silex, lime, and iron. This mi- being calcined and dissolved in nitro-muriatic acid, the solution is to be neutralized by caustic potash, and then treated with tar- trate of potash. The precipitate, well washed and afterwards calcined, is pure oxide of ce- rium. • This oxide, which is white, when calcined in the open air becomes red and ac- quires more oxygen. These oxides, parti cu J larly the white, are soluble in most acids; the red oxide with muriatic acid gives oxy- muriatic acid.
The experiments hitherto made on this sub- ject scarcely enable us to decide respecting the proportions of metal and oxygen, nor the relative weights of these oxides.
Both Vauquelin* and Hisingerf agree that the proto-carbonate of cerium, when expo- sed to a red heat, yields 57 or 58 oxide, which the former says is the red oxide, being
* An. de Chimie, 54—28 fAii.ofPhilos.— 4—356
METALLIC OXIDES. 95
changed by the calcination. Hisinger finds the percarbonate to consist of 36.2 acid and 63.8 oxide : also that the muriate of cerium consists of 100 acid and 197.5 oxide; but Vauquelin remarks that the sulphate, nitrate, and muriate of cerium are always more or less acid, however dried; and he found the protoxalate of cerium to yield 45.6 red oxide by calcination, on a mean of 3 experiments not much differing from each other. Sup- posing all these facts accurate, they may be reconciled by a few suppositions by no means improbable. Let the atom of cerium be 22, the protoxide 29, and the red oxide 32§ (that is, 1 oxy. 4- 2 protox. =65)', and let the protocarbonate be 1 atom of acid, 1 of oxide, and 1 of water; the percarbonate, 1 acid 1 oxide; the oxalate, 1 acid (40) and 1 oxide; and the muriate, saturated with base, 3 ox- ide and 2 acid. Then it will be found that,
The decomposed protocarbonate will yield 57.5 red oxide; The decomposed percarbonate will yield, 36.7 acid, 63.3
oxide; The decomposed oxalate will yield 47 red oxide; and The muriate will yield 100 acid (22), and 197.7 oxide.
All of which agree very nearly with the re- sults above obtained.
96 SULPHURETS.
Hence it appears to me very probable that the several atoms of the metal and the oxides are as stated above; and that,
100 cerium + 31.8 oxygen = 131.8 protoxide, white
f- 47.7 — — ■ =• 147.7 intermediate, red.
Hisinger, from some of the same data uni- ted to other hypothetical facts than those as- sumed above, deduces the two oxides very different; viz. 100 metal 4- 17.4 oxygen for the protoxide, and 100 + 26.1 for the per- oxide.
SECTION 14.
EARTHY, ALKALINE AND METALLIC SULPHURETS.
The sulphurets exhibit a very important class of combinations of two elements. Many of the metals are found chiefly in the state of native sulphurets, and are extracted by par- ticular processes. Artificial combinations of sulphur and the metals, and of sulphur and the earths and alkalies are commonly prac- tised, and are found useful in chemical inves-
SULPHURETS. 97
ligations. The alkaline and earthy sulphu- rets will scarcely be allowed perhaps to be combinations of two elements only ; but their analogy with the other compounds is such as to induce us to treat of them under this head, especially as they are agents occasionally in the formation of metallic sulphurets, and these cannot be so well understood without some knowledge of the other. For like reasons the compounds of three elements, sulphur, metal, and oxygen, called sulphuretted ox- ides, and sulphuretted sulphites, and those of four elements, sulphur, metal, oxygen and hy- drogen, called hy drosulphurets, may be con- sidered at the same time, having an intimate relation with the sulphurets strictly so called, or the compounds formed with sulphur and the undecompounded bodies.
Sulphur may be combined with the earths, alkalies and metals, by heat, of various de- grees according to the nature of the subjects. The union is attended in many cases with a glowing ignition, indicating the evolution of heat. The metallic oxides and sulphur when heated together commonly produce a sulphu- ret of the metal, whilst the oxygen escapes with part of the redundant sulphur in the form of sulphurous acid, and the rest of the sul- phur sublimes.
VOL. II. K
98 SULPHURETS.
In the humid way sulphur may be combined with earths, alkalies, and metals, by means of sulphuretted hydrogen, hydrosulphurets (that is, sulphuretted hydrogen united to other alka- line or earthy bases), and hydroguretted sul- phurets (a name given to certain earthy and alkaline sulphurets formed mostly by boiling mixtures of the respective bases and sulphur in water.) The sulphuretted hydrogen may be used in this state of gas or combined with water; the hydrosulphurets and hydro- guretted sulphurets are best applied in their watery solutions. The metals are to be used in this case in the state of salts, that is, ox- ides united to acids, and in solution; or their oxides may in some instances be precipitated previously to the addition of the sulphur com- pound ; the alkalies and earths are sometimes directly sulphurized in the state of hydrates, and at other times by double affinity, in the state of salts or combined with acids. The phenomena in the case of sulphurets formed in the humid way, are various and often com- plicated, and the true results are not always to be obtained without considerable difficulty and uncertainty.
tIME. 99
1. Sulphurets of lime.
When pounded liine and sulphur are mixed together, and heated in a crucible scarcely any union takes place; the sulphur sublimes or burns away and leaves the lime unaltered. If for lime we substitute carbonate of lime, it also remains unaltered. But if hydrate of lime and sulphur are heated together in equal weights, the hydrate is decomposed, and the lime unites to a portion of the sulphur, whilst the excess of sulphur sublimes or burns and escapes at a low red heat. The residue, about 60 per cent, of the original weight, is a yel- lowish white powder, composed of sulphur and lime. If this be again treated with sul- phur and heated, it undergoes no material change; the last sulphur entirely escaping, leaves the sulphuret unaltered, and hence shews that it must be a true chemical com- pound.
Now if 32 parts hydrate of lime, which consist of 24 lime and 8 water, be mixed with 32 sulphur and heated as above, they will yield 38 parts sulphuret, which must be com- posed of 24 lime and 14 sulphur, or sulphur and water; but it appears from the analysis
100 SULPHURETS.
hereafter to be given, that the whole of this last part is sulphur; therefore the compound is formed of 1 atom of lime, and 1 of sulphur, and is the protosulpkuret of lime.
When 32 parts of common hydrate of lime and 56 sulphur, are boiled together in 1000 parts water for half an hour, or more, occasion- ally adding water to supply the waste, a fine yellow liquid is obtained, with a few grains of residuum containing both lime and sulphur nearly in the original proportion with a few grains of alumine. This liquid of course contains in solution, a combination of 1 atom of lime, or perhaps hydrate of lime, and 4 atoms of sulphur ; and may therefore be called a quadrisulphuret of lime. If more sulphur or lime than the above proportion be used, the surplus will remain in the residuum uncom- bined, shewing that by this process no other than a quadrisulphuret can be formed. A similar solution may be obtained in cold water by frequent agitation; bflt it is much slower in producing the effect. The strength of li- quid quadrisulphuret depends upon the relative quantity of the ingredients. I have boiled it down till the water was only 5 times the other materials, which appears to be its maximum strength in the common temperature; its spe-
LIME. 101
cific gravity was 1.146; but in general I have used it of less than 1.07 density. It may be proper to remark here that I find the decimals multiplied by 4 express very nearly the num- ber of grains of lime in 1000 grains measures of the solution, and multiplied by 9 those of the sulphur; on this account a solution of the sp. gravity 1.06 facilitates the calculations, as 100 measures of it contain 2.4 grains of lime, and 5.4 or 5.6 of sulphur nearly.
It is rather surprising that no bisulphuret nor trisulphuret of lime should be formed this way. One would suppose that the sul- phuret of lime in its progressive changes would have passed through the forms of bi- sulphuret, &c. till it had obtained itsmaximum of sulphur when that was in excess; but, as has been observed, the quadrisulphuret is the only one formed, whatever may be the proportions of the ingredients. I imagine the reason to be, that the sulphur has to de- compose the hydrate of lime, and that no fewer than 4 atoms of sulphur are adequate to that effect; it is known that water adheres so strongly to lime as to require a red heat to separate it. When therefore we mix lime water with quadrisulphuret of lime, it must be considered as a mere mixture of the two, and that the lime does not divide the sulphur
10£ SULPHURETS.
Equally. Consistently with this reasoning, whenever the lime is in excess in forming qua- drisulphuret of lime, we ought to consider the liquid solution as lime watey holding qua- drisulphuret of lime. This distinction will be of some importance when the solution is weak, because then the lime in the lime water will be considerable, compared with the lime combined with sulphur.
1. Protosulphuret. The properties of this compound are; — about 1 grain is soluble in 1000 water; this water, as well as the powder itself, tastes like the white of an egg; salts of lead are thrown down black by the solu- tion; weak nitric and muriatic acids dissolve the lime, and leave the sulphur; 100 parts of test acid require 19 of the powder, and yield 7 of sulphur; indicating the compound to be 12 lime and 7 sulphur. The same conclusion may be obtained by means of a solution of lead; if water containing 1.9 grains of the powder be precipitated by nitrate of lead, it will require 7 grains of the salt = 2.2 acid and 4.8 oxide, or 4.5 lead, and about 5 or 5 J grains of sulphuret of lead will be formed, and the liquid will contain 3.4 grains of neu- tral nitrate of lime.
2. Quadrisulphuret. This combination has been long known, and some of its properties
LIME. 103
observed; but I have not found in authors any determination of its proportions. It is of a beautiful yellow or orange colour, and 1 grain imparts very sensible colour to 1000 of water; it has a disagreeable bitter taste; when evaporated down, it crystallizes or ra* ther perhaps solidifies into a yellowish mass; but its properties are affected by the process from the acquisition of oxygen. This mass when dried, burns with a blue flame and loses 40 per cent. ; the remainder is a white powder, a mixture of sulphite and protosulphuret of lime. Liquid quadrisulphuret exposed to the atmosphere soon becomes covered with a white film which arises from the sulphur displaced by oxygen gas; this film being broken subsides, and another is formed, and so on successively till at length the acquisition of oxygen ceases with the deposition of sulphur, and the li- quid remains quite colourless. It is intensely bitter, and contains lime, sulphur and oxygen in proportions to be presently determined. This colourless liquor undergoes a gradual change by being kept for years in a bottle with a common cork ; a deposition of some sulphur and sulphate of lime takes place, but whether from a further acquisition of oxygen gas or from some internal chemical action, I have not had an opportunity of observing.
104 SULPHURETS.
From the above observations it is obvious that to form pure quadrisulphuret of lime the atmospheric air should be excluded, as the agitation by ebullition would promote the oxi- dizement of the compound. I mixed 168 grains of sublimed sulphur with 96 hydrate of lime, which by previous trials I had found to consist of 70 lime including1 2 or 3 grains of alumine, and 26 water; the mixture was put into a small florence flask, which was then filled with water up to the neck and loosely corked. This was immersed in a pan of water and boiled for 2 or 3 hours, the flask was continually turned round to agitate the mixture and promote the solution. After the undissolved part had subsided the clear liquor was decanted an d found to be 2800 grain measures of the sp. gr. 1.056; the residuum moderately dried weighed 34 grains ; it was found to contain 8 of lime and alumine, and 25 of sulphur. Hence the liquid contained 62 lime and 143 sulphur, or 2.2 lime and 5.1 sulphur per cent. ; that is, after the rate of 24 lime to 56 sulphur, or 1 atom of lime to 4 of sulphur, and its weight = 80, the atom of sulphur being supposed 14. Here then we have a synthetic proof of the composition be- ing a quadrisulphuret. Innumerable other experiments, though made with less rigid ac-
LIME. 105
curacy, had convinced me that the liquid is essentially the same whatever the proportions of the ingredients, and that the residuum only varies in such cases.
I have made many experiments occasionally since 1805, on the quantities of oxygen ab- sorbed and sulphur deposited by quadrisulphu- ret of lime. They all concur in establishing the same conclusion ; namely, that each atom of the compound takes 2 of oxygen and de- posits 2 of sulphur, in its transformation from the yellow to the colourless state. For in- stance, 100 measures of the above 1.056 took 900 of oxygen gas == 1.22 grains, and let fall 2 grains of sulphur, besides a small portion which adhered to the bottle, which was esti- mated at a few tenths of a grain. The me- thod is to put 100 measures into a graduated and well stoppered bottle filled with oxygen; to agitate briskly for half an hour, occasion- ally opening the stopper a little under water to admit its entrance into the place of the oxygen absorbed. Whenever the agitation has been continued for five minutes without any sensible increase in absorption, and the liquor, after standing to let the sulphur subside, ap- pears colourless, the experiment is finished. This new combination then consists of 1 atom lime, 2 sulphur, and 2 oxygen = 66; it will
VOL. II. O
106 SULPHURETS.
be necessary to give it a name : I propose calling* it sulphuretted sulphite of lime, as it is an atom of sulphur united to sulphite of lime; and the rather, as it will appear in the sequel that other neutral salts do combine oc- casionally with an atom of sulphur. This sulphuretted sulphite may be boiled down to the sp. gr. 1.1 before it precipitates: the li- quid then contains about 12 per cent, of the salt, or 5 sulphur, 2§ oxygen, and 4| lime. The salt precipitates from the liquid by eva- poration in the form of a white powder; it burns with a feeble blue flame, and loses about 20 per cent. ; the remainder is sulphite of lime. When 100 grain measures of the liquid sul- phuretted sulphite (1.1) are saturated with oxymuriate of lime, they acquire 5 grains of oxygen, and then yield 12| grains of sulphu- ric acid (containing 5 sulphur and 7{ oxygen), as may be found by the barytic tests. The point of saturation is known by the smell of oxymuriatic acid being given out perma- nently.
If however we oxidize the quadrisulphuret of lime by oxymuriate of lime, the results are somewhat different. As soon as an atom of the quadrisulphuret has received two atoms of oxygen it becomes colourless as before, but f of the sulphur is thrown down instead of § ;
LIME.- 107
and when more oxyinuriate is added, so as to impart 3 atoms of oxygen to one of the salt, a complete sulphate of lime is formed. The point of saturation is determined by adding a small portion of muriatic acid to the liquid, which developes the oxymuriatic acid as soon as it becomes in excess. This method e eels in the analysis of the alkaline and earthy sulphurets in general.
When quadrisulphuret of lime is treated with an alkaline carbonate, a reciprocal change takes place; the carbonic acid takes the lime, and the alkali the sulphur, leaving however 1 atom of sulphur with the carbonate which precipitates. Hence a sulphuretted carbonate of lime is obtained and a trisulphuret of the alkali. The sulphur burns off from the car- bonate below a red heat and leaves 75 per cent, of carbonate of lime; this affords an excellent analysis of quadrisulphuret of lime as far as lime is the object. Thus 540 of the above 1.056 quadrisulphuret took 100 test carbonate of potash (1.25), and gave a pre- cipitate of 29 grains, which burned blue and left 22 grains = 12 lime, and 10 acid ; but if 540 : 12 :: 100: 2.2, as above determined synthetically : moreover, 12 lime, 10 acid, and 7 sulphur, are as 24 lime, 20 acid, and 14 sulphur; the composition of an atom of sul-
108 SULPHURETS.
phuretted carbonate of lime, which is analo- gous to the sulphuretted sulphite of lime, as found above.
When quadrisulphuret of lime is treated with as much sulphuric acid as is sufficient for the lime, the sulphur is in part precipitated, but it is in union with the sulphate of lime, or at least they are not separable by mechani- cal means. This compound is sold in the shops under the name of precipitated sulphur. It is about one half sulphate of lime, and the other half sulphur. The nitric and mu- riatic acids precipitate the sulphur partially from quadrisulphuret, but the sulphur assumes a viscid form and exhales sulphuretted hydro- gen, and the proportion of the elements of quadrisulphuret are not easily obtained by any of these acids.
The mutual action of quadrisulphuret of lime, and the metallic salts is curious and in- teresting ; for instance, with nitrate of lead. Let a solution of nitrate of lead, containing 97 oxide, be treated with a solution of qua- drisulphuret of lime by degrees, as long as a black precipitate appears, marking the ex* act point of saturation ; this will be found when 36 parts of lime have entered, and 84 of sul- phur; the sulphuret of lead will fall, and When dried will weigh 145 parts, and contain
LIME. 109
90 lead, and 55 sulphur ; that is, 1 atom of lead, and 4 of sulphur, and is consequently a quadrisulphuret of lead. The liquid re- mains clear and colourless, and contains the nitric acid, lime, oxygen of the lead, and -^ of the sulphur ; each atom of nitric acid com- bines with one of lime, which retains one of the 4 atoms of sulphur, forming a sul- phuretted nitrate of lime, consisting of 45 acid, 24 lime, and 14 sulphur; the 7 parts of oxygen unite with 7 of sulphur to form sulphurous acid, which require 12 parts of lime to saturate them and 7 of sulphur, form- ing a sulphuretted sulphite of lime : hence we see that 28 parts of sulphur remain in the liquor, and the rest (56) unite with the lead. If now we add gradually more nitrate of lead, a silvery white precipitate appears, increasing till half the original quantity is added, and then the liquid is saturated. This white pre- cipitate is sulphuretted sulphite of lead; when heated it soon grows black and loses 15 or 20 percent., being then a protosulphuretof lead. The liquid now contains sulphuretted nitrate and simple nitrate of lime; nitrate of lead has no effect, but nitrate of mercury preci- pitates a black sulphuret.
Quadrisulphuret of lime saturated with oxy- gen, as has been observed, contains sulphu-
110 SULPHURETS.
retted sulphite of lime in solution, and de- posits sulphur : the liquid treated with nitrate of lead, gives as above the white, silvery sul- phuretted sulphite of lead as a precipitate, and holds nitrate of lime in solution.
Hydrosulphuret of lime. This compound may be formed by passing sulphuretted hy- drogen into lime water; the water assumes a brownish colour, but the point of saturation is not easily found, as the lime water is not neu- tralized so as to shew by the colpur test, and water of itself absorbs above twice its volume of the gas. By means of a neutral solution of nitrate of lead it may be found that 1000 lime water in volume, require about 600 sulphuretted hydrogen, because then a mutual saturation is observed by dou- ble affinity; that is, sulphuret of lead and neutral nitrate of lime are formed; but other- wise the liquid remaining is either acid or al- kaline. Hydrosulphuret of lime, as well as the other hydrosulphurets, has a peculiar bit- ter taste. It forms a useful reagent in regard to metals, but is apt to be spoiled by keeping? owing to the acquisition of oxygen*
MAGNESIA. Ill
2. Sulphuret of magnesia,
I have not succeeded in endeavouring to combine sulphur and magnesia in the dry way ; but a liquid sulphuret is easily formed by the action of double affinity.
Let a quantity of the liquid quadrisulphu- ret of lime be treated with a solution of sul- phate of magnesia, so that the sulphuric acid may be sufficient for the lime; by digesting in a moderate heat, the sulphate of lime is precipitated, carrying with it one fourth of the sulphur, and a trisulphuret of magnesia remains in solution. I have not observed any remarkable feature of distinction between this sulphuret and that of lime, except as above noticed in the proportions of their com- pounds.
Hydrosulphuret of magnesia. This com- pound may be formed by pouring sulphuret- ted hydrogen water into recently precipitated magnesia; it does not differ much from that, of lime. One atom of sulphuretted hydro- gen (15), combines with one of magnesia (17), and the compound is soluble in water.
112 SULPHURETS.
3. Sulphur et of barytes.
Protosulphuret. The protosulphuret of ba- rytes may be procured the same way as that of lime, by heating hydrate of barytes and sulphur till the mixture becomes red. It is very little soluble in water, and accords in other respects with the like compound of lime. It consists of 68 barytes and 14 sulphur, or 100 barytes and 20| sulphur.
Quadrisulphuret. The quadrisulphuret of barytes may be formed the same way as qua- drisulphuret of lime, by boiling the hydrate of barytes and sulphur together. A yellow solution of the compound is formed, not dis- tinguishable in appearance from that of lime ; and it appears to be analogous to it in most of its properties. By acquiring oxygen it be- comes colourless sulphuretted sulphite of ba- rytes, and crystalizes in needles; in this last respect it differs from that of lime. The maxi- mum density of liquid quadrisulphuret I have not had an opportunity of ascertaining ; it is 1.07 or upwards; that of the liquid sulphuret- ted sulphite is much less than that of lime ; the crystals are found in a liquid so low as 1.004 sp. gr. They have a fine silky lustre when dry, and a yellowish colour; heated
STRONTLTES. 113
they burn with a blue flame and leave a white mass of sulphate preserving the same crystal- line appearance as before, and lose about 20 per cent, of weight. Ten grains of the crys- tals of sulphuretted sulphite, when treated with liquid oxymuriate of lime to safuration, require 2-f- grains of oxygen and yield 8 grains of sulphate of barytes, together with an ex- cess of sulphuric acid which with muriate of barytes gives 8 grains more of sulphate. From these facts it may be concluded that the sulphuretted sulphite consists of one atom ba- rytes, 2 sulphur, 2 oxygen, and 2 water, and that 4 more of oxygen are derived from the oxymuriatic acid to convert the sulphur- ous oxide into sulphuric acid. The sulphu- retted sulphite of barytes seems to pass into sulphate by length of time. The weight of the atom of quadrisulphuret of barytes is 124; the compound in mass consists of 100 barytes and 82 sulphur.
Hydrosulphuret of barytes. This com- pound may be formed in the same manner as that of lime, and is found to have similar properties. The proportions for mutual sa- turation are, I find, as in the case of lime, 15 sulphuretted hydrogen to 68 barytes by weight, or one atom of each.
VOL. II. P
114 SULPHURETS.
4. Sulphurels of strontites.
The protosulphuret and quadrisulphuret of strontites may be formed in the same way as those of lime and barytes. From a few ex- periments made on these compounds I have not observed any remarkable feature of dis- tinction between them and the correspond- ing ones of the other earths.
Hydrosulphuret of strontites. This com- pound may be formed in the same way as that of lime; the proportions to produce mutual saturation will be 1 atom of each, or 15 parts sulphuretted hydrogen, to 46 strontites by weight.
5, 6*7, 8, and 9. Sulphur ets ofalumine, silex, yttria, glucine, and zircone.
I made several unsuccessful attempts to combine alumine and sulphur. When alu- mine and sulphur mixed together are heated, the sulphur sublimes chiefly, and leaves the alumine with traces of sulphate of alumine.
In the humid way, recently precipitated and moist alumine mixed with sulphur and
POTASH. 115
boiled in water, give a liquid with some tra- ces of sulphuric acid, but no sulphuret of alumine; the sulphur and alumine both sub- side, and when the sulphur is either sublimed or burnt, the alumine remains much the same as at first. When a solution of alum is treated with sulphuret of lime, sulphate of lime is precipitated along* with the greatest part of the sulphur in a kind of feeble union rather than mechanical mixture, it should seem ; the alumine is at the same time pre- cipitated probably in mechanical mixture; there remain in solution a little sulphuret of potash and sulphate of lime.
Sulphuret of silex is not known, I appre- hend, to exist. When silicated potash in so- lution is treated with quadrisulphnret of lime, a copious dark brown or black precipitate in- stantly appears; the liquid when filtered is of a pale yellow colour, and seems to contain about one half of the sulphur and potash, whilst the other half is thrown down in union with the lime and silex. This black compound is probably 1 atom of lime, 2 of sulphur, 2 of potash, and 2 of silex; it can- not therefore be accounted a sulphuret of silex.
Sulphurets of yttria, glucine% and zircone, are as yet, I presume, unknown.
116 SUI/PHURETS.
10. Sulphurets of potash.
Potash has a strong affinity for sulphur and unites with it in various ways and pro- portions.
1st. In the dry way by heat. When either pure potash or the carbonate (salt of tartar) is heated in a covered crucible with sulphur, a chemical union of the two principles takes place. Eight parts of dried hydrate of pot- ash unite to six or seven of sulphur: a heat of 4 or 500° of Fahrenheit is convenient for the purpose. If the carbonate of potash be used* then 12 parts dried in a low red heat will re- quire 8 of sulphur for their complete satu- ration : in this case a higher degree of heat is requisite in order to expel the carbonic acid; alow red heat seems sufficient from my trials. When the heat does not exceed 3 or 400° a partial union takes place; the carbonate of potash, without losing any acid, unites to ^ of the sulphur, and the rest of the sulphur remains uncombined; when intermediate de- grees of heat are used, I have found the re- sult a mixture of the pure sulphuret and the carbonated sulphuret, with more or less of sulphate of potash. A high degree of heat and exposure to the atmosphere produces a
POTASH. 117
sulphate instead of a sulphuret. The sul- phurets obtained this way are in fusion till poured out and cooled ; they are of a liver colour, and hence were formerly called livers of sulphur. They are largely soluble in wa- ter, and give a brownish yellow solution.
2d. In the humid way by solution. Pure caustic potash in solution when boiled with sulphur dissolves it largely, 42 parts of real potash being saturated with about 56 of sul- phur. If we boil a solution of carbonate of potash with sulphur, for an hour or more, a brown liquor is obtained, which consists of 60 parts carbonate of potash and 14 sulphur in chemical union. — It has already been ob- served that a trisulphuret of potash may be obtained by double affinity from quadrisul- phuret of lime and carbonate of potash, to- gether with sulphuretted carbonate of lime.
From what has been stated we may infer at least three varieties in the compounds of sul- phur and potash, viz. 1
1st. Sulphuretted carbonate of potash, ^his consists of 1 atom carbonate of potash (61) with I atom of sulphur (14). Its analysis may be effected as follows : the quantity of carbonic acid may be found by the lime water necessary to saturate it ; the potash may be known from the quantity previously entering
118 SULPHURETS.
into the mixture; and the sulphur in the same manner, or from the quantity of sul- phuretted carbonate of lead that it forms. — The sulphur may also be known, from the quantity of oxygen it requires by means of oxymuriate of lime to produce saturation ; this I find to take place when the oxygen is half the weight of the sulphur, or one atom to one of sulphur ; it soon happens, that one atom of sulphur deprives two others of their oxygen, and sulphuric acid is formed whilst the other two atoms of sulphur join the car- bonate of lime and are precipitated along with it. As it may frequently happen, that the sulphuretted carbonate is mixed with common carbonate of potash, the propor- tions may be found by means of nitrate of lead, which being cautiously dropped into the solution, lets fall first the brown sulphu- retted carbonate of lead, and then the com- mon white carbonate of lead.
The sulphuretted carbonate of potash ab- sorb oxygen and precipitates metals much the same in appearance as the other sulphu- rets; but essential distinctions are observable, some of which are noticed above, and others will appear in the sequel.
2 and 3. The irisulphuret and quadrisul~ phuret of potash so nearly resemble the qua-
AMMONIA. 119
drisulphuret of lime in their properties, as not to require any additional remarks.
Hydrosulphuret of potash. This combina- tion, when duly proportioned, consists of 15 parts sulphuretted hydrogen, and 42 potash by weight, or one atom of each. It may be formed by directly uniting* the two elements, or by decomposing hydrosulphuret of lime by carbonate of potash. Its properties agree with those of the other hydrosulphurets.
11. Sulphur ets of soda.
I have repeated most of the experiments on the sulphurization of potash with soda, and have not found anyone remarkable feature of distinction, besides those which arise from the weights of the atoms.
1 . Sulphuretted carbonate of soda consists of 1 atom of carbonate of soda united to 1 of sulphur ; or of 47 parts of the former and 14 of the latter.
2. Trisulphuret of soda consists of 1 atom soda (28) and 3 of sulphur (42).
3. Quadrisulphuret of soda consists of 1 atom soda (28) and 4 atoms of sulphur (56).
Hydrosulphuret of soda. This compound consists'of one atom of each of the elements,
120 SULPHURETS.
or 15 sulphuretted hydrogen, and 28 soda, In other respects it agrees with hydrosulphu- ret of potash.
12. Sulphuret of ammonia,
The best way which I have found of pro- curing sulphuret of ammonia, is to treat qua- drisuiphuret of lime with the carbonate of ammonia as long as any precipitate takes place ; the precipitate is sulphuretted carbo- nate of lime, 3 atoms of sulphur to 1 of carbonate of lime. The liquid is of a pale yellow, and contains ammonia and sulphur united in the ratio of 1 atom (of 6) to 1 of sulphur: it may therefore be denomi- nated the protosulphuret of ammonia.
The carbonate of ammonia is best procur- ed by heating the common subcarbonate of, ammonia, first pulverized, in a temperature of 100° for half an hour, or exposing it for a few days to the atmosphere. What remains of the salt is almost without smell; it should consist of 19 parts acid, 6 ammonia, and 8 water nearly : the ammonia is usually however a small degree in excess.
Hydromlphuret of ammonia. This com- pound may be formed in the dry state by com-
GOLD. 121
bining- the two gases of sulphuretted hydro- gen and ammonia over mercury; it is of a white crystalline appearance, and very solu- ble in water, and forms a fuming liquor of a very pungent smell. It may also be obtained by passing sulphuretted hydrogen into a ves- sel containing liquid ammonia. I find about 110 or 120 measures of sulphuretted hydrogen require 100 of ammoniacal gas. Hence it is 1 atom of sulphuretted hydrogen (15), that unites to 1 of ammonia (6).
13. Sulphurets of gold.
There exist at least two sulphurets of gold, the nature and proportions of which are ea- sily ascertained \ though several authors as- sert that no combinations of gold and sul- phur are known; amongst these it is surpriz- ing to find Proust : indeed most of the others have probably been led by his authority to adopt the opinion without examination. It is not very easy to account for his deception.
Obercampf, in the Annal. de Chimie, torn. 80. 1811, is the first author I have seen who distinctly maintains the existence of one or more sulphurets of gold, though it seems to have been admitted previously by Bucholz. The last author finds 82 gold unite to 18 sul- phur, and the former 80 to 20 nearly.
vol. it. a
122 SULPHURETS.
Prolosulphuret of gold. This compound is formed whenever a solution of muriate of gold is agitated with sulphuretted hydrogen gas, or with the same united to a base, as lime or alkali. A black or deep brown pow- der falls down by the addition of more gas, till the whole of the gold is precipitated. The oxide of gold loses one atom of oxygen, and receives one of sulphur in its place, whilst the hydrogen of the gas is carried off along with the oxygen of the oxide. The sulphuret dried and heated, burns with a blue flame, leaving the gold nearly pure. This compound consists, I find, of 81 gold and 19 sulphur per cent.; or 100 gold unite to 23 sulphur.
Trisulphuret of gold. This compound is obtained whenever quadrisulphuret of lime is gradually dropped into a solution of mu- riate of gold ; it is a black powder, not quite so deep as the former. Care must be taken to saturate the excess of acid previously by lime-water, to prevent any uncombined sul- phur precipitating. Trisulphuret of gold be- ing heated, burns with a blue flame, and leaves the gold nearly pure; it loses from 40 to 45 per cent, by the process. It is constituted of 1 atom gold and 3 sulphur, or 60 gold
PLATINA. 123
and 42 sulphur, nearly ; or 100 gold combine with 70 sulphur.
From several experiments I am led to con- clude that each atom of oxide of gold takes 3 of sulphur, and parts with 1 of oxygen to the remaining sulphur; thus a trisulphuret of gold is formed, and an oxide of sulphur ; the liquid, being afterwards treated withoxymu- riate of lime, is found to require twice the oxygen of the gold for its saturation, when a corresponding portion of sulphuric acid may be precipitated by muriate of barytes.
14. Stdplmret of platina.
Sulphur may be combined with platina in several ways, and probably in different pro- portions; but the combination is not so easily and elegantly effected as with many other me- tals, and hence some uncertainty still remains on the subject.
When a salt of platina is treated with sul- phuret or hydrosulphuret of lime, or sulphu- retted hydrogen water, the liquid slowly and gradually grows dark brown and finally black ; after agitation and standing a few hours, the liquid is semitransparent, and a black floccu- lent precipitate appears at the bottom . Some- times after violent agitation, the liquid on stand- ing a few minutes becomes a transparent brown ,
124 SULPHURETS.
but soon grows turbid again. In the course of a few days, and by occasional agitation, the liquid finally becomes clear and nearly free from platina, and the precipitate may be col- lected on a filter and dried. This circum- stance of slow and indolent precipitatiou can- not be prevented by any means I have found, such as saturating the excess of acid, &c.
Mr. Edmund Davy, in the 40th Vol. of the Philos. Magazine, has given us the results of his experiments and observations on the sul- phurets of platina, containing some useful and original information. He combines platina with sulphur by heating the ammonia-muriate of platina with sulphur; also by heating1 pla- tina and sulphur in an exhausted tube; and by sending sulphuretted hydrogen gas or wa- ter into a solution of muriate of platina; this precipitate he calls hydrosulphuret of platina.
He has just noticed the precipitate formed by sulphuret of potash with muriate of pla- tina, but gives no opinion as to the compound obtained this way. He determines three sul- phurets, namely,
Subsulphuret, 100 platina + 19 sulphur
Sulphuret, 100 -f 28.2
Supersulphuret, 100 -f 38.8
I have obtained the sulphuret of platina in five ways : 1st. By pouring sulphuret of lime
PLATINA. 125
solution by degrees into muriate of platina, and agitating the mixture well or till it grew black each time; after digesting for some days, repeated filtering, and drying, a black powder is obtained: 2. Instead of suiphuret, hydrosulphuret of lime was used; the preci- pitate was obtained under like circumstances : 3d. Sulphuretted hydrogen water was used, and the precipitate obtained in like manner : 4th. Ten grains of ammonia-muriate of pla- tina were treated with sulphuretted hydro- gen water; by, continued agitation the yellow powder disappeared, the liquid looked uni- formly black, and at length a precipitate was formed; by ^repeated filtration and addition of sulphuretted hydrogen water, the whole of the platina was thrown down, and the liquid remained colourless; but it is difficult to discover the exact quantity of sulphuretted hydrogen requisite for any weight of the am- monia-muriate from the tediousness of the operation; 6 grains of well dried black pow- der were obtained, besides perhaps 1 grain of loss on the filters: 5th. Ammonia-muriate of platina was heated in a covered crucible along with sulphur till it was judged that all the uncombined sulphur was sublimed or dis- sipated.
All these sulphurets appear to me to be the
126 SULPHURETS.
same when dried in a moderate heat. When exposed to a low red heat they yield water and sulphurous acid, and lose about £ of their weight.
The subject however, requires further in- vestigation. The sulphurets of platina ap- pear of a complex nature, and the propor- tions of their elements are not yet determined with precision.
15. Sutyhurets of silver.
Silver combines with sulphur in two diffe- rent proportions, and forms two sulphurets, both of them black or dark brown.
1. Protosidphuret of silver. This may be formed either by the dry or humid way : if thin lamina of silver be heated with sulphur, they combine and form this sulphuret; a higher degree of heat expels the sulphur again. It is formed too by passing sulphuretted hy- drogen or a hydrosulphuret through a solu- tion of silver in nitric or other acids. The atom of silver unites with that of sulphur, whilst the hydrogen unites with the oxygen. Of course this compound is composed of 90 silver, and 14 sulphur, and the atom weighs 104; or 100 silver unite with 15.5 sulphur. Klaproth finds 100 silver and 17.6 sulphur; Wenzel 100 silver, and 14.7 sulphur; Ber-
MERCURY. 127
zelius 100 silver, and 14.9 sulphur \ and Vau- quelin 100 silver, and 14 sulphur.
Trisulphuret of silver. This compound is formed whenever neutral nitrate of silver is dropped into a solution of quadrisulphuret of lime or alkali. Mutual saturation seems to take place when eight atoms of nitrate meet with seven of quadrisulphuret. Tri- sulphuret of silver is constituted of 90 silver, and 42 sulphur; orof 100 silver, and 46.5 sul- phur. Its colour is not so dark as that of the protosulphuret. The residuary liquid con- tains sulphurous acid, which is easily con- verted into sulphuric by the addition of a por- tion of lime; and the quantity of acid may then be determined by muriate of barytes.
16. Sulphur ets of mercury.
Mercury combines readily with sulphur both in the dry and humid way, and that in several proportions, as under: namely,
1. Protosulphuret of mercury . This is most conveniently formed by passing sulphuretted hydrogen gas through a solution of the pro- tonitrateof mercury, or by pouring hydrosul- phuret of lime, &c. into the same solution. The protosulphuret falls down in the state of a black powder. • It consists of 167 mercury,
128 SITLPHURETS.
and 14 sulphur; or of 100 mercury, and 8.4 sulphur. The theory of its formation is the same 'as' that of silver.
2. Deutosulphuret of 'mercury. This is form- ed in the humid way whenever sulphuretted hydrogen or ahydrosulphuret in excess is mix- ed with the deutonitrate or deutomuriate of mercury (corrosive sublimate) ; a brown pow- der is precipitated which is the deutosulphu- ret. If the sulphuretted hydrogen be only one half what is sufficient to form the deutosul- phuret, then we obtain no sulphuret, but in- stead of it a protonitrate or protomuriate, as was first intimated by Proust ; I find however, the atom of sulphur adheres to the atom of salt, and that it is therefore a sulphuretted protonitrate or muriate, whilst 1 atom of oxygen unites with the hydrogen. The brown precipitate does not change to yellow, orange, and red, when left undisturbed for a few days, in my experience; though this is stated to have been observed by Mr. Accum. Not- withstanding the difference in colour, this deutosulphuret must be the same nearly as the cinnabar and Vermillion of commerce, if Proust and others are right in their analysis of thes« articles. The combination of the ele- ments of sulphur and mercury when intended to form cinnabar is made in the dry way by tri-
MERCURY. 129
turation, and a moderate heat; the compound, at first black, is afterwards sublimed by a duly regulated heat and becomes red. This compound must consist of 100 mercury and 17 sulphur nearly.
3. Quadrisulphuret of mercury. This com- pound is formed when a solution of protoni- trate of mercury is treated with quadrisulphu- ret of lime, added by degrees till the clear liquid no longer gives a dark coloured precipi- tate. The oxygen of the mercurial salt unites, it should seem, to part of the sulphur, and forms sulphuric acid, whilst the rest of the sulphur unites to the mercury. This sulphuret is a black or dark brown powder, and when heated burns with a blue flame. It consists of 100 mercury, and 33 or 34 sulphur, as ap- pears to me from the synthesis.
When the insoluble muriate of mercury (calomel), is triturated in liquid quadrisul- phuret of lime, it is soon decomposed ; qua- drisulphuret of mercury is formed, with mu- riate of lime and sulphuric or sulphurous acid.
When the soluble muriate (corrosive subli- mate), has quadrisulphuret of lime dropped into it by degrees ; at first a yellowish white precipitate is obtained, which increases till it is one half saturated \ after this, by conti-
VOL. II. R
130 SULPHURETS.
nually adding" more sulphuret, the precipitate grows darker, and ends in being1 quite black. It is at least as high as quadrisulphuret. Much sulphurous acid is found in the liquid.
The deutonitrate of mercury, produces a copious yellow precipitate with quadrisul- phuret of lime. Exposed to the sun, it grows black in a few minutes on the light side, but continues yellow on the opposite side of the jar; at the same time, an effer- vescence and disengagement of oxygen gas are observed. Finally, the precipitate be- comes the common quadrisulphuret, and the liquid contains sulphurous and sulphuric acids.
The recently precipitated and washed ox- ides of mercury act upon quadrisulphuret of lime. The black oxide seems to take 4 atoms of sulphur and part with its oxygen to another portion of sulphur; but the red oxide becomes light brown and retains the colour when dried. It seems to take the same sul- phur as the black, but whether it retains any of the oxygen, I have not ascertained. The action is more slow than when the nitrates are used, and more quadrisulphuret of lime is ex- pedient.
Mercury and sulphur combine in the dry way by trituration and by heat, forming a black powder; but the species of compounds
PALLADIUM. 131
and quantities of the ingredients combining in this mode, have not been ascertained.
17. Sulphur et of palladium. '{
Berzelius exposed 15 grains of palladium filings mixed with as much sulphur to a heat sufficient to expel the uncombined sulphur. The increase of weight was 28 per cent, upon the palladium ; when exposed afresh with sul- phur to heat, no addition was made to the weight.
Vauquelin heated 100 parts of the triple salt of palladium with an equal weight of sul- phur, and obtained 52 parts of a blueish white sulphuret, very hard, and when broken ex- hibiting brilliant plates in its fracture. He had previously found that TOO salt contained 40 to 42 of metal : hence 100 metal combin- ed with from 24 to 30 of sulphur. This agrees nearly with the above results of Berze-r lius. A very high degree of heat expels the sulphur and oxidizes the metal ; but a more moderate heat leaves the palladium of a silver white colour and nearly pure. According to this the atom of protosulphuret of palladium must consist of 50 palladium, and 14 sul- phur.
132 SULPHURETS.
18. Sulphur et of rhodium.
Vauquelin found that 4 parts of the ammo- nia-muriate of rhodium (containing 28 or 29 percent, of metal) being* mixed with an equal weight of sulphur, and heated, a blueish white button was obtained, weighing 1.4. Hence 100 metal seem to take 25 of sulphur ; and allowing this to be the protosulphuret of rhodium, the atom must consist of one rhodium 56, and one sulphur 14, making the whole weight 70.
19. Sulphuret of iridium.
According to Vauquelin, 100 parts of the ammonia-muriate of iridium heated with as much sulphur, ^ield 60 parts of black powder resembling^the other metallic sulphurets ; but 100 parts of the salt were found to yield from 42 to 45 of metal. Now supposing the last number the most correct, it should seem that 3 parts iridium take 1 sulphur, or 100 take 33|. This being supposed the protosulphuret, the atom of iridium must be 42, and that of the sulphuret 56.
20. Sulphuret of osmium.
It is as yet unknown whether any combi- nation of sulphur and osmium exists.
COPPER. 133
21. Sulphur ets of copper.
Copper readily unites with sulphur both in the dry and humid way. When 3 parts of copper filings are mixed with 1 part of sul- phur, and heat applied, a brilliant combus- tion ensues, which indicates the union of the two bodies. Copper leaf burns in the fumes of sulphur, as fierzelius has observed, with great brilliancy.
The protosalphuret of copper obtained by these similar methods, when pulverized, is black or dark coloured; it has been analyzed by various authors, who nearly agree in their results. Proust finds 100 copper unite with 28 sulphur; Wenzel, 100 copper and 25 sul- phur; Vauquelin, 100 copper and 27 sulphur; and Berzelius 100 copper and 25 sulphur.
If the atom of copper be 56, and that of sulphur 14, the atom of protosulphuret of copper will be 70; which gives just 100 cop- per and 25 sulphur.
The protosulphuret may also be formed in the humid way, by sending sulphuretted hy- drogen gas or a hydrosulphuret into a solution of protomuriate of copper, or amongst the recently precipitated protoxide of copper.
Deutosulphuret of copper. This compound is formed whenever sulphuretted hydrogen gas
134 SULPHURETS.
or a hydrosulphuret is sent into a solution of salt containing the deutoxide, or into the deutoxide just precipitated from any acid. It is a dark brown powder not differing much in appearance from the protosulphuret. It con- sists of 100 copper and 50 sulphur; the weight of the atom is 84.
Quadrisulphuret of copper. This compound is formed by mixing quadrisulphuret of lime with a salt of the deutoxide of copper, and diluting the solution. A light brown precipi- tate falls immediately, which is the quadri- sulphuret of copper. It burns with* a blue flame, and leaves the protosulphuret. The atom consists of 56 copper and 56 sulphur, or weighs 112; and hence the sulphuret con- sists of equal parts copper and sulphur.
The blue hydrate of copper recently preci- pitated from a salt of copper and washed, acts upon quadrisulphuret of lime ; the results, ac- cording to my experience, is quadrisulphuret of copper, and the oxygen unites with the sulphur remaining in the liquor.
22. Sulphurets of iron.
Sulphur may be united to iron either by the dry or humid way, and that in various pro- portions.
IRON. 135
Protosulphuret of iron. This compound may be formed by passing a hydrosulphuret into a solution of the green oxide in any acid. It is a black powder. It may also be formed by rubbing a highly heated bar of iron with a roll of sulphur; the two unite in a fluid form and soon congeal into a brownish black mass. It is too a natural production, though not very common; excellent analyses of it, as well as of the common pyrites, were some time ago given by Mr. Hatchett. (See Nicholson's Journ. Vol. 10.) The protosulphuret is mag- netic in a considerable degree; it is soluble in acids, and yields sulphuretted hydrogen. It is proper to notice that the sulphuret of iron is not precipitated from solutions by sulphu- retted hydrogen simply or without a base. According to Mr. Hatchett this sulphuret consists of 100 iron, and 57 sulphur, which corresponds with 1 atom iron 25, and 1 of sul- phur, 14, nearly.
Deutosulphuret of- iron. This is a natural production frequently met with, and in vari- ous forms; it is called pyrites, or iron pyrites; it is a yellowish mineral and often appears when broken, of a radiated texture, but sometimes it is crystallized in cubes or do- decaedrons. Acids have little effect upon it, except the nitric, which when diluted attacks
136 SULPHURETS.
both the sulphur and iron ; much nitrous gas is produced, the iron is dissolved, and the sulphur chiefly converted into sulphuric acid. This sulphuret consists, according to Proust, of 100 iron, and 90 sulphur, and with this Bucholz recently agrees (Nichols. 27 — 356) ; but Hatchett makes it 100 iron, and 112 sul- phur. From an experiment of my own on the radiated pyrites, I found nearly equal parts of iron and sulphur. One atom of iron (25,) and two of sulphur (28,) would give 100 to 112; but if the atom of sulphur be only 13, it gives 100 iron to 104 sulphur. Mr. Hatchett un- fortunately calculating the proportions of the ingredients in 100 sulphuret, instead of on 100 iron, did not notice that the sulphur in the common pyrites is just double of that in the magnetic pyrites.
Quinsulphuret of iron. This combination consisting of 5 atoms of sulphur with 1 of iron, is formed by mixing a solution of green sul- phate of iron with quadrisulphuret of lime in due proportion. I found 50 measures sulphate 1.168 saturate 310 of 1.05 sulphuret diluted so as to become 6 oz. ; this yielded 14 grs. dried sulphuret of iron — 3.6 iron, known to be in the sulphate, and 10.4 sulphur ; the liquid con- tained 2+ sulphur combined with the lime and oxygen of the oxide; for it took 2.3 oxygen
IRON. 137
by means of oxymuriate of lime to convert the sulphur into sulphuric acid together with 1 + from the oxide, making 3 + oxygen, which unites to 2+ sulphur to constitute 5+ sulphuricacid; and this quantity of acid was found to exist by muriate of barytes together with five more brought in by the sulphate of iron. This sulphuret is a yellowish brown powder ; it readily exhales sulphur by heat and is reduced to the protosulphuret; but in the open air it burns with a blue flame and leaves the protosulphuret partially, as I apprehend, oxidized. The theory of the formation of quinsulphuret seems to be this: 3 atoms of quadrisulphuret of lime are requisite to satu- rate 2 of sulphate of iron ; the 2 atoms of sul- phuric acid seize 2 of lime, three fourths of the sulphur unite to the iron, and one fourth to its oxygen, forming 2 atoms of oxide of sulphur, which attack the 3d atom of sul- phuret and decompose it, giving its sulphur to the iron, and neutralizing the lime (for the liquid is found neutral). In this way 10 atoms of sulphur are united to 2 of iron, and 2 of sulphur to 2 of oxygen, with one of lime, which last compound remains in solution, and the oxide of sulphur may be conver- ted into sulphuric acid immediately by the application of oxymuriate of lime.
VOL. II. S
138 SULPHURETS.
It is remarkable that neither the green nor the yellow oxides of iron, even when recently precipitated and not dried, seems capable of decomposing quadrisulphuret of lime.
It is probable that trisulphuret and quadri- sulphuret of iron may be formed ; but I have not ascertained the truth of this opinion.
23. Sulphur els of nickel.
Prolosuiphuret. According to Proust, nickel unites to sulphur by heat, so that 100 take 46 or 48; the sulphuret is of the colour of com- mon pyrites. (Journ.de Physique, 63 and ■80). According to Mr. Ed. Davy 100 nickel take ,54. sulphur. By saturating a solution of nitrate of nickel with hydrosulphuret of lime I obtained 40 grains from 33 protoxide or 26 metal. This was evidently the protosulphu- ret ; it was a fine black powder, and consists pf 100 metal and 54 sulphur.
Quinsulphuret. This compound may be ob- tained from nitrate of nickel and quadrisul- phuret of lime, in the same manner as that of iron. It is a deep black powder, and consists of 100 nickel, and 215 sulphur. By expo- sure to heat, the greatest part of the sulphur burns off, and the rest may be expelled by an increase of temperature.
Probably intermediate sulphu rets - may be
TIN. 139
formed; but I have not pursued the investi- gation.
24. Sulphur ets of tin.
Sulphur and tin unite both in the dry and humid way, and in various proportions.
Protosulphuret. This may be readily form- ed in the dry way as follows; let 100 grains of tin be fused in a small iron ladle and heated to 6 or 8 hundred degrees Fahrenheit; let then small pieces of sulphur of 10 or 20 grains be successively dropped into the fused metal : a copious blue flame will instantly arise each time, and a glowing heat will take place, when the sulphur and tin are in contact; as soon as this ceases, another fragment of sulphur must be dropped in, and this two or three times repeated, heating it at last to a perfect red; the mass may then be taken out and pounded in a mortar ; a great part of it will be a pulverulent powdery but some portions of malleable metal will still be mixed with it, which may be separated by a sieve. This must be again heated and treated with sulphur as before, and the whole mass will be converted to a sulphuret. I find that 100 parts of tin become in this way 127 grains ; which is the due proportion of 52 tin and 14 sulphur, so that no loss of tin is sustained by
140 SULPHUKETS.
the process when duly managed. According to Wenzel, 100 tin take 18 sulphur ; Berg- man, 25; Pelletier, 15 to 20; Proust, 20; but Dr. John Davy and Berzelius find nearly 27 as above stated, and I have no doubt it is near the truth.
The protosulphuret of tin is a dark grey shining powder, with a streak like molybde- na or plumbago; it is not ;much different in colour and appearance from native sulphuret of antimony, only less blue. It is soluble in muriatic acid by heat, and yields sulphuretted hydrogen and protomuriate of tin.
Deutosulphuret. This compound is better known than the former : it may be formed in various ways; one is by heating a mixture of deutoxide of tin and sulphur in a retort almost to a red heat ; sulphur sublimes and sulphur- ous acid is disengaged, and there remains a yellow, light shining, flaky mass at the bottom of the retort which is the sulphuret. It was formerly called aurum musivum or mosaic gold. Pelletier and Proust were of opinion that this product is a sulphuretted oxide of tin; but Dr. John Davy and Berzelius have rendered it more probable that it is a true deutosulphu- ret, consisting of 100 tin and 54 sulphur. It is insoluble in muriatic or nitric acid, but slowly soluble by the compound of the two acids; it
TIN. 141
is also soluble in potash by heat. By expos- ing it to a bright red heat, it burns with a blue flame and leaves a yellowish powder which does not seem to differ much from proto- sulphuret.
Berzelius distilled a mixture of protosul- phuret and sulphur at a low red heat, and ob- tained a mass of a yellow grey colour and metallic lustre, which consisted of 100 tin, and 14 sulphur, which is just the mean sul- phur between the other two. This would seem to indicate that a compound of the two sulphurets, 1 atom to 1, is capable of being formed.
Hydrosulphuret of tin minor. This com- pound is formed according to Proust, when sulphuretted hydrogen, or an alkaline or ear- thy hydrosulphuret is passed into a solution of protomuriate of tin. It is of a brown or dark coffee colour when precipitated, and black when dried. By heat it yields water and protosulphuret. From some experiments I am inclined to believe, that it is formed of 1 atom protosulphuret and 1 of water: or, which is the same, 1 atom protoxide of tin and 1 of sulphuretted hydrogen, If this be right it may be said to be a compound of 100 tin, 27 sulphur and 15 water.
Hydrosulphuret of tin major. This name is
142 SULFHURETS.
given by Proust to the yellow compound thrown down by sulphuretted hydrogen or by hydrosulphurets from solutions of the deutox- ide of tin. When dried moderately, the precipitate is of a dull yellow colour, and vi- treous fracture, but I find it is almost black, dried in a heat of 150° or upwards. By mo- derate heat it yields water, sulphurous acid, sulphur, and the residue is deutosulphuret of tin according to Proust. I heated 4 parts of the above previously dried so as to become a black vitreous powder ; it burned feebly with a blue flame, and after being made mode- rately red, left nearly 3 parts exactly resem- bling the artificial protosulphuret. I believe the dried precipitate will be found to be con- stituted of 1 atom tin, 2 sulphur and 1 water; that is, 100 tin, 54 sulphur and 15 water = 169 by weight ; and that it loses 27 sulphur and 15 water by a red heat, which reduces the weight just one-fourth.
Quinsulphuret of tin. This is obtained in the humid way, by first precipitating the ox- ide, and then putting quadrisulphuret of lime or potash to the liquid containing the precipi- tate, till the liquid after agitation and subsi- dence of the precipitate continues of a yel- lowish colour. I found that 31 measures of protomuriate of tin of 1.377 = 7 grains acid,
TIN. 143
7.5 tin and 1 oxygen, precipitated by 10 oz. lime water, required 450 measures of 1.40 sulphuret of lime, containing* 16 sulphur and 7.2 lime, for their saturation. The residuary liquid was nearly colourless, and the precipi- tate dried in an oven of 100* or more, for 10 hours, weighed 17 grains besides loss in the ope- ration. It was a yellow, vitreous mass, and when pulverized and heated, burned with a blue flame, and lost 40 per cent, in weight; the residue was a yellow grey colour, and seemed to be like the intermediate sulphuret of Berzelius ; it would not give sulphuretted hydrogen by hot muriatic acid. Now if 52 (1 atom tin) : 70 (5 atoms sulphur) ; : 7.5 tin : 10 + sulphur; hence the sulphuret should have weighed 17.5 grains, which was the observed weight, allowing § grain for loss. According to this, 100 tin combine with 135 sulphur, and when burnt, the 235 are redu- ced to 140, the weight observed by Berzelius in the instance alluded to. The liquid requir- ed 5 grains of oxygen from oxy muriate of lime, to convert the sulphur into sulphuric acid, and the weight of this acid, found by muriate of barytes, was 11 grains, indicating 4.4 sulphur. It may be observed that the 4.4 grains, and 10 grains, do not make up the whole (16) of the sulphuret of lime; but the
144 SULPHURETS.
reason I apprehend was, that the quadrisul- phuret was old, and did not contain the full share of sulphur, it being- usual for a small part to fall by-time.
The deutomuriate of tin, precipitating1 the oxide in like manner, yielded a sulphuret ra- ther lighter yellow than the above; about 10 tin gave 25 grains of sulphuret dried in a temperature of 80 to 100°. This compound still contained water, and 1 suspect it will be found constituted of 1 atom tin, 5 sulphur, and 2 water.
25. Sulphurets of lead.
Lead combines with sulphur in various pro- portions, some of which are natural produc- tions of great purity.
Protosulphuret. This is a natural produc- tion which is called galena; it is of lead grey colour and metallic appearance, and is found both in masses and crystallized; its sp. gr. is about 7.5. It may be formed artificially by heating lead or its oxide with sulphur; also by treating a solution of lead with sulphuretted hydrogen or with a hydrosulphuret. Authors are well agreed as to the proportions of the ingredients; 100 lead combine with from 15 to 16 sulphur. That is, 90 lead with 14 sul- phur; orl atom of lead withl of sulphur.
LEAD. 145
Deutosulphuret. Dr. Thomson mentions a natural production or species of galena which contains twice the quantity of sulphur of that above. I have reason to believe that this compound is easily formed in the humid way, by treating the precipitated oxide with the due quantity of quadrisulphuret of lime.
Trisulphuret and quadrisulphuret. These compounds, I find, may be formed by means of quadrisulphuret of lime or potash. When a solution of any salt of lead or the recently precipitated and moist oxide, is treated with the requisite quantity of quadrisulphuret of lime, a combination consisting of 1 atom of lead and 3 of sulphur is formed. It is a black powder not differing much in appearance2 from the protosulphuret; it is lighter and more spongy. It consists of 100 lead and 46 or 47 sulphur. The due proportions of the ele- ments to form the above compound are, lead 100 parts in solution, and sulphur, 62 parts; \ of the sulphur is retained by the lime, and may be converted into sulphuric acid instantly by the addition of as much oxymuriate of lime as contains oxygen equal in weight to the sulphur, as it has already as much oxygen as converts it into sulphurous oxide, derived from the oxide of lead. Quadrisulphuret of lead is to be obtained la
VOL. II. T
146 SULPHURETS.
the same way ; only we must have an excess of the sulphuret of lime, or more than 80 sul- phur for 100 lead in solution, as ^ part of the sulphur at least is retained by the lime. The quadrisulphuret is a black powder like the others; it burns with a blue flame and loses nearly 40 per cent., the residue being" still black. It consists of 100 lead and 62 sul- phur.
I have not ascertained whether any higher sulphuret of lead is capable of being formed this way.
It has been already noticed (page 109), that a beautiful white, silvery sulphuretted sulphite of lead is formed and gradually pre- cipitated, when nitrate of lead is dropped into a solution where as much black quadrisulphu- ret of lead has been just thrown down as the sulphuret of lime can form.
26. Sulplmrets of zinc.
• Zinc and sulphur are scarcely to be united
directly by heat ; but by heating the oxide of
zinc and sulphur together, a combination is
effected; part of the sulphur carries off the
oxygen in sulphurous acid, and part combines
with the zinc. Mineralogists give the name
zinc. 147
of blende to a mineral which is chiefly the protosulphuret of zinc : its colour is yellow- ish, brown, or black almost like galena: its specific gravity is usually 3.9 or 4.
Protosulphuret. The above artificial com- pound, or the mineral, may be taken as ex- amples of the union of 1 atom zinc and 1 sulphur. But the most correct and conveni- ent way of forming it for the purpose of che- mical investiagtion is, to drop a given portion of some salt of zinc into a dilute hydrosul- phuret. A white precipitate falls, which when dried becomes a dark cream colour. It is found to consist of 2 parts zinc and 1 of sulphur nearly; that is, of 29 parts zinc and 14 sulphur.
Deutosulphuret, trisulphuret, &c. of zinc. These combinations may be made, up to the 5th or quinsulphuret, in the humid way by qua- drisulphuret of lime, &c. The oxide may be first precipitated by lime water, or not, as we please, and then treated with quadrisulphu- ret according to the degree of sulphuration required. I found 100 measures of 1.29 ni- trate of zinc with 2500 of 1.026 sulphuret of lime yield 40 grs. dry sulphuret zinc, of a yellowish white colour; the liquid was found to retain 13 or 14 grains of sulphur, by con- verting it into sulphuric acid by means of
148 SULPHURETS.
oxymuriate of lime. The nitrate contained llf zinc and 2.8 oxygen; so that about 28 sulphur had combined with the zinc, and about 14 remained in solution, or 4. of the whole, as has been already explained. By proportion, if 11 f : 28 : : 29 : 70; or 1 atom of zinc (29) combines with 5 atoms of sul- phur (70). The intermediate combinations I have not particularly examined ; they do not differ much in appearance from the one just described; they burn blue and are redu- ced by it to the protosulphuret ; and they give sulphuretted hydrogen by muriatic acid.
27 and 28. Sulphur ets of potassium and sodium.
•According to Davy and Gay Lussac, po- tassium and sodium unite with sulphur by heat with vivid combustion. The compounds appear to be protosulphurets, that of potash being nearly as 35 potassium to 14 sulphur, and that of sodium as 21 sodium to 14 sul- phur. When potassium and sodium are heat- ed along with sulphuretted hydrogen, an uni- on likewise takes place; two atoms of gas unite to one of the metals, except that 1 atom of hydrogen is liberated, corresponding of course in quantity to that liberated by treating
BISMUTH. 149
them with water. When the compound thus formed is treated with muriatic or sulphuric acid, the same quantity of sulphuretted hy- drogen nearly is liberated that was originally combined. So that the compound may be regarded as sulphuretted hydrogen united to the protosulphurets. The colour of these sul- phurets varies from grey to yellowor reddish.
29. Sulphurets of bismuth.
Protosulphuret. Bismuth combines with sul- phur by heat, in the manner already described in the account of tin sulphurets. I found 100 parts bismuth in this way combine with 22 sulphur after 4 operations : this is therefore the protosulphuret or 1 atom bismuth (62) with 1 of sulphur (14). It may also be formed by substituting the oxide of bismuth for the me- tal. It has a dark brown or black metallic appearance, much like that of tin. It yields sulphuretted hydrogen in heated muriatic acid.
Hydrosulphuret of bismuth. When a solu- tion of bismuth in nitro-muriatic acid i» dropped into hydrosulphuret of lime, a black powder precipitates, which, when dried in the common temperature, appears to be hydro- sulphuret of bismuth, or one atom sulphu-
150 SULPHURETS.
retted hydrogen and one oxide of bismuth. It yields sulphuretted hydrogen by cold muriatic acid. But if the precipitate be dried in a heat of about 200°, the atom of water seems to be expelled, and there remains only the protosulphuret. Thus I found 69 parts ox- ide of bismuth unite to 15 sulphuretted hy- drogen to form 84 hydrosulphuret of bismuth, when dried in the air; but upon being heated a little, it lost 8 parts of water and was redu- ced to the protosulphuret, retaining in great part the same appearance as before.
Deutosulphuret and trisulphuret of bismuth with oxygen. When nitro-muriate of bismuth is thrown into water the oxide is precipitated ; if the acid water be decanted, quadrisulphu- ret of lime be put to the moist oxide and due agitation be used, the oxide abstracts sul- phur from the lime so as to obtain 2 or 3 atoms for each one, if the sulphur be suffici- ent in quantity. To 6 oz. water I put 100 grain measures of 1.286 nitro-muriate, which I knew from its formation contained 20 ox- ide; after the precipitate had subsided I poured off 5 oz. of acid water, and to the re- maining precipitate diluted with water I put 300 of 1 .056 sulphuret of lime and agitated for 10 minutes. There were obtained 33 grains of brownish black sulphuret of bis-
ANTIMONY. 151
niuth dried for some hours in a temperature of 120°. I put the above 33 grains into a gas bot- tle with 100 muriatic acid and boiled it ; there were obtained only 2 or 3 cubic inches of sul- phuretted hydrogen, the oxide was dissolved and sulphur liberated; the sulphur collected and dried weighed 9 grains, and the oxide precipitated again from the muriatic acid by water and dried, weighed 17 grains, besides loss. From this it is evident the oxygen of the oxide must have been chiefly retained in the compound, and must have united to 2, and in great part to 3, atoms of sulphur. For 20 oxide would require 12 sulphur to form trisulphuretted oxide; and there was evidence of its having nearly, if not wholly, that quantity.
30. Siilphurets of antimony.
Protosulphuret. This is a natural produc- tion, and found in the state of a dark grey mineral of metallic appearance, and of the sp. gr. 4.2. It may also be formed artificially by uniting metallic antimony and sulphur by heat. Most authors nearly concur in assign- ing to it 74 parts antimony and %Q sulphur, per cent. That is, 1 atom antimony (40) and and 1 of sulphur (14). It yields sulphuretted
152 SULPHTXRETS.
hydrogen by muriatic acid and heat, and a solution of the metallic oxide is obtained.
Hydrosulplmret. When antimony is preci- pitated from a solution, by sulphuretted hy- drogen or a hydrosulphuret, or from an alka- line solution of the sulphuret by an acid, it ap- pears in the form of an orange yellow pow- der, denominated golden sulphuret. It is constituted of 1 atom sulphuretted hydrogen and 1 of protoxide of antimony; it readily yields sulphuretted hydrogen by muriatic acid, and the oxide combines with this acid. Ex- posed to heat, water is expelled and protosul- phuret left. It is constituted of 40 antimony, 7 oxygen, 14 sulphur and 1 hydrogen; or of 54 protosulphuret and 8 water.
Bisulphuretted, trisulphuretted and quadri- sulphuretted oxide of antimony. When crystal- lized muriate of antimony is agitated along with dilute quadrisulphuret of lime, an orange yellow compound- is formed, consisting of the oxide and sulphur. To 350 quadrisulphuret of lime> diluted with lime water, I put 22 grains moist crystals of muriate, and agitated well for some time. Got 26 grains dry yellow sul- phuret, which heated burned blue, and left from 13 to 14 black grey sulphuret, equal to 10 antimony nearly ; hence it must have been a quadrisulphuret, or rather sulphuretted ox-
TELLURIUM. 153
ide ; for, by heating this compound in muri- atic acid, a solution is obtained and sulphur liberated without the extrication of gas. Less of the sulphuret of lime would have produ- ced a sulphuret of the same colour, but con- taining less of sulphur; so that it is evi- dent various proportions may exist in combi- nation. Instead of the crystallized muriate, the recently precipitated oxide, nearly free from acid, may be used to produce these compounds.
31. Sulphuret of tellurium.
Tellurium unites with nearly its weight of sulphur, by heat, according to Davy. It is probable that as usual in such cases, a proto- sulphuret is formed. This would lead to the conclusion that the atom of tellurium is only equal in weight to that of sulphur; which does not accord with results from the other combinations of tellurium, and hence the above fact may riot perhaps be sufficiently ascertained.
32. Sulphurets of arsenic.
Arsenic may be combined with sulphur by exposing a mixture of the metal and sulphur or of the white oxide and sulphur, to a heat
VOL. II. U
154 SULPHURETS.
approaching to redness. In the latter case more sulphur is required, because the oxygen is carried off in the shape of sulphurous acid. Three parts of arsenic with two, three or more of sulphur may be used; the heat should be less if a greater proportion of sulphur is in- tended to be united. As both the elements are volatile in a moderate heat, and that in unequal degrees, considerable difficulty occurs in ascertaining by the synthetic mode, the proportions of the elements combined; if too little heat be used, only a mechanical mixture is obtained, of any proportions we please; if too much heat be used, part of the arsenic as well as part of the sulphur sublimes, and the sulphuret itself sublimes at a heat not much exceeding that required for their union. Hence, in a great measure we have the dis- cordant results of those who have taken the synthetic method. The analytic method is to be preferred, and those who have taken it have succeeded the best; but even this is at- tended with greater difficulties than with most of the other sulphurets.
The artificial sulphurets of arsenic consti- tute two varieties chiefly, and these are also found native in various parts of the earth.
1; Protosulphuret* Native sulphuret: of ar- senic* called orpiment, is found in Turkey
ARSENIC. 155
and elsewhere in considerable masses; when broken it exhibits a foliated structure, some- what flexible, and of a brilliant golden yel- low colour. Its specific gravity is usually about 3.2; at least that was the case with, the specimen I used. When heated so as to be near melting, its surface reddens, probably by the loss of sulphur. The same sulphuret is procured artificially in the humid way whenever a solution of the oxide of