Part 9
_Quinsulphuret of tin._ This is obtained in the humid way, by first precipitating the oxide, and then putting quadrisulphuret of lime or potash to the liquid containing the precipitate, till the liquid after agitation and subsidence of the precipitate continues of a yellowish colour. I found that 31 measures of protomuriate of tin of 1.377 = 7 grains acid, 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 precipitate dried in an oven of 100° or more, for 10 hours, weighed 17 grains besides loss in the operation. 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 ½ grain for loss. According to this, 100 tin combine with 135 sulphur, and when burnt, the 235 are reduced to 140, the weight observed by Berzelius in the instance alluded to. The liquid required 5 grains of oxygen from oxymuriate 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 reason I apprehend was, that the quadrisulphuret 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, precipitating the oxide in like manner, yielded a sulphuret rather 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 I 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 proportions, some of which are natural productions of great purity.
_Protosulphuret._ This is a natural production 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 sulphur; or 1 atom of lead with 1 of sulphur.
_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 appearance from the protosulphuret; it is lighter and more spongy. It consists of 100 lead and 46 or 47 sulphur. The due proportions of the elements to form the above compound are, lead 100 parts in solution, and sulphur, 62 parts; ¼ 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 in the same way; only we must have an excess of the sulphuret of lime, or more than 80 sulphur for 100 lead in solution, as ⅕ 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 sulphur.
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 precipitated, when nitrate of lead is dropped into a solution where as much black quadrisulphuret of lead has been just thrown down as the sulphuret of lime can form.
26. _Sulphurets 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 of _blende_ to a mineral which is chiefly the protosulphuret of zinc: its colour is yellowish, brown, or black almost like galena: its specific gravity is usually 3.9 or 4.
_Protosulphuret._ The above artificial compound, or the mineral, may be taken as examples of the union of 1 atom zinc and 1 sulphur. But the most correct and convenient way of forming it for the purpose of chemical investigation is, to drop a given portion of some salt of zinc into a dilute hydrosulphuret. 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 quadrisulphuret of lime, &c. The oxide may be first precipitated by lime water, or not, as we please, and then treated with quadrisulphuret according to the degree of sulphuration required. I found 100 measures of 1.29 nitrate 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 converting it into sulphuric acid by means of oxymuriate of lime. The nitrate contained 11½ zinc and 2.8 oxygen; so that about 28 sulphur had combined with the zinc, and about 14 remained in solution, or ⅓ of the whole, as has been already explained. By proportion, if 11½ ∶ 28 ∷ 29 ∶ 70; or 1 atom of zinc (29) combines with 5 atoms of sulphur (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 reduced by it to the protosulphuret; and they give sulphuretted hydrogen by muriatic acid.
27 _and_ 28. _Sulphurets of potassium and sodium._
According to Davy and Gay Lussac, potassium 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 sulphur. When potassium and sodium are heated along with sulphuretted hydrogen, an union 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 them with water. When the compound thus formed is treated with muriatic or sulphuric acid, the same quantity of sulphuretted hydrogen 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 sulphurets varies from grey to yellow or reddish.
29. _Sulphurets of bismuth._
_Protosulphuret._ Bismuth combines with sulphur 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 metal. 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 solution of bismuth in nitro-muriatic acid is dropped into hydrosulphuret of lime, a black powder precipitates, which, when dried in the common temperature, appears to be hydrosulphuret of bismuth, or one atom sulphuretted 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 oxide of bismuth unite to 15 sulphuretted hydrogen 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 reduced 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, quadrisulphuret of lime be put to the moist oxide and due agitation be used, the oxide abstracts sulphur from the lime so as to obtain 2 or 3 atoms for each one, if the sulphur be sufficient in quantity. To 6 oz. water I put 100 grain measures of 1.286 nitro-muriate, which I knew from its formation contained 20 oxide; after the precipitate had subsided I poured off 5 oz. of acid water, and to the remaining 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 bismuth dried for some hours in a temperature of 120°. I put the above 33 grains into a gas bottle with 100 muriatic acid and boiled it; there were obtained only 2 or 3 cubic inches of sulphuretted 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. _Sulphurets of antimony._
_Protosulphuret._ This is a natural production, 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 assigning to it 74 parts antimony and 26 sulphur, per cent. That is, 1 atom antimony (40) and 1 of sulphur (14). It yields sulphuretted hydrogen by muriatic acid and heat, and a solution of the metallic oxide is obtained.
_Hydrosulphuret._ When antimony is precipitated from a solution, by sulphuretted hydrogen or a hydrosulphuret, or from an alkaline solution of the sulphuret by an acid, it appears in the form of an orange yellow powder, 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. Exposed to heat, water is expelled and protosulphuret left. It is constituted of 40 antimony, 7 oxygen, 14 sulphur and 1 hydrogen; or of 54 protosulphuret and 8 water.
_Bisulphuretted_, _trisulphuretted_ and _quadrisulphuretted oxide of antimony_. When crystallized 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 sulphuret, 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 oxide; for, by heating this compound in muriatic acid, a solution is obtained and sulphur liberated without the extrication of gas. Less of the sulphuret of lime would have produced a sulphuret of the same colour, but containing less of sulphur; so that it is evident various proportions may exist in combination. 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 protosulphuret 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 not 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 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 intended 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 discordant 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 attended with greater difficulties than with most of the other sulphurets.
The artificial sulphurets of arsenic constitute two varieties chiefly, and these are also found native in various parts of the earth.
_Protosulphuret._ Native sulphuret of arsenic, called orpiment, is found in Turkey and elsewhere in considerable masses; when broken it exhibits a foliated structure, somewhat flexible, and of a brilliant golden yellow 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 arsenic in water, &c. is treated with sulphuretted hydrogen, or a hydrosulphuret, and afterwards with an acid; or when this or any other species of sulphuret of arsenic is dissolved in an alkali and the solution treated with an acid. Kirwan in 1796 states, that it is generally thought to consist of 100 arsenic and 11 sulphur, but that Westrumb says it contains 100 arsenic and 400 sulphur, which Kirwan thinks more probable; they are both however very wide of the truth. Thenard, in the 59 VOL. of the An. de Chimie, 1806, asserts that it consists of 100 arsenic and 75 sulphur; but he does not point out the experiments on which this result rests; and it is not very near the truth. Laugier in the same An. VOL. 85, for 1813, in a paper of great merit, finds the native orpiment to contain 38 per cent. of sulphur; his method is to dissolve the orpiment in warm dilute nitric acid; to precipitate the sulphuric acid by nitrate of barytes, and from the sulphate of barytes infer the sulphur; the rest he considers as arsenic, not knowing how to detach the arsenic acid from the nitric acid so as to determine the arsenic by experiment. I have pursued this method with the advantage of being able to determine the arsenic as well as the sulphur: Ten grains of orpiment in fine powder were dissolved in 100 measures of 1.346 nitric acid diluted with as much water, by digesting in a heat so as to keep a constant moderate effervescence for about 2 hours. The liquid obtained, being diluted, yielded 536 measures of 1.061. By carefully and gradually dropping in muriate of barytes I found 150 measures of 1.162 just sufficient to saturate the sulphuric acid, and the sulphate of barytes produced dry was 28 grains, the loss I estimated 1 grain: now one third part being sulphuric acid, and ⅖ of the acid being sulphur, we have ²/₁₅ of 29 = 3.87, or 3.9 for sulphur. The residuary liquid was then treated with lime water till an excess was manifest, and produced no farther precipitate; the arseniate of lime was collected and dried, and gave 16 grains. Now I had determined by experiments hereafter to be related, that ⁴/₇ of arseniate of lime are acid and ⅔ of the acid are arsenic; hence ⁸/₂₁ of 16 = 6.1 for the arsenic, which added to 3.9 sulphur, make up the 10 grains of orpiment.
When this orpiment is treated with caustic alkali, it is completely dissolved; it is thrown down by acids I find unaltered. If 61 arsenic combine with 39 sulphur, 100 must take 64 nearly; which corresponds with 1 atom of each, or 21 arsenic + 13 or 14 sulphur.
_Subprotosulphuret._ Sulphur and arsenic are found native in certain places, combined in masses of a brownish red or orange colour and glassy fracture: this combination is called _realgar_, and is also manufactured in large quantities in Saxony, chiefly for the use of calico-printers. Its constitution and specific gravity vary considerably, owing chiefly I imagine to the greater or less heat to which it is exposed, and to the proportions of the elements in the first mixture. I have specimens of 3.3 and 3.7 sp. gr.; and it is probable these are not the extremes; the heaviest is the darkest colour. Of course the heaviest contains the most arsenic, and I have reason to believe that the sp. gr. is nearly as good a test of the proportions of the elements as chemical analysis. Realga when pulverized is of an orange colour: it is much sooner dissolved in dilute nitric acid and requires less, than the same weight of orpiment. Caustic alkali dissolves it partially, taking up the protosulphuret and leaving the excess of arsenic, the quantity of which may hence be ascertained. Ten grains of realgar took 80 measures of 1.347 nitric acid, diluted with as much water; digested in a heat of about 150° it was all dissolved in 1½ hour, and yielded 536 liquid of 1.05 sp. gravity. This treated as before gave 24 sulphate of barytes = 3.2 sulphur, and 18 arseniate of lime = 6.9 arsenic. This result agrees nearly with Laugier’s in regard to the sulphur in native realgar: but the artificial realgar, which he made by combining arsenic and sulphur, yielded him 40 per cent. sulphur by my estimation and 42 by his own: the sp. gravity of his artificial realgar is not given. Westrumb estimates realgar at 100 arsenic and 25 sulphur, and Thenard at 100 arsenic and 33 sulphur. But from the above it must be concluded to contain 100 arsenic and 45 to 50 of sulphur. One hundred parts of the same realgar heated in caustic potash were resolved into 78 orpiment taken up by the liquid and 22 arsenic precipitated.
It appears to me most probable that a true subsulphuret would be most convenient for the printers’ use, or one containing 100 arsenic and 32 sulphur, that is, 2 atoms arsenic and 1 sulphur. The object being to deoxidize indigo and obtain it in solution in a green state, we may suppose that 1 atom arsenic takes the oxygen from the indigo and then forms arseniate of lime which precipitates, whilst the other atom in union with the sulphur, takes the green indigo and unites it to the potash, making a quadruple compound of arsenic, sulphur, green indigo and potash in solution. If this view be right the heaviest and darkest coloured realgar of commerce must be the most advantageous for this purpose. Some printers however prefer the protosulphuret.
_Deutosulphuret._ Proust, by heating 100 arsenic with 300 sulphur in one instance got 222 parts, and in another 234 parts of a transparent deep greenish yellow sulphuret, (Jour. de Phys. 59--p. 406. 1804). Now it is very remarkable that if we take the atom of sulphur at 13 and that of arsenic 21, one of this and two of the former will be found as 100 to 124, together 224; but if sulphur be 14, then the proportion will be 100 to 133, together 233. It seems more than probable that Proust had accidentally used that degree of heat in the combination which is requisite for forming the deutosulphuret. It is probable too that Laugier always used a higher heat, as he uniformly obtained the same (lower) sulphuret whatever were the proportions, the excess of either being sublimed or separated by the heat.
_Trisulphuret_, _quadrisulphuret_, &c. When a solution of the oxide of arsenic is treated with quadrisulphuret of lime, little precipitate appears; but if muriatic acid be dropped in, a fine yellow precipitate is formed. This I have reason to think is sometimes a trisulphuret, and at other times a quadrisulphuret or higher; but it is difficult to investigate these compounds, and on that account I speak with some uncertainty.
33. _Sulphuret of cobalt._
Sulphuretted hydrogen does not precipitate cobalt from solutions containing that metal; but hydrosulphurets precipitate it.
_Protosulphuret._ This compound is obtained whenever a neutral solution of cobalt is treated with hydrosulphuret of lime, &c. or it may be obtained from any acid solution by first precipitating the blue oxide by an alkali, and then introducing sulphuretted hydrogen into the mixture. By this last method I found a solution previously known to contain 44 parts by weight of protoxide to absorb 15 parts of sulphuretted hydrogen; when filtered and dried in a heat of 100° it yielded 51 parts of protosulphuret. In appearance it resembles many of the other black sulphurets. It consists of 100 cobalt and 38 sulphur; Proust finds 40 sulphur, but he considers it only an approximation.
The same sulphuret may be formed by heating the oxides of cobalt and sulphur together to a red heat; at least a combination is effected as Proust observed, but I have not investigated the proportions. Sulphur does not seem to combine with the metal in this way.
_Deutosulphuret_ ... _dodecasulphuret_. When the recently precipitated and moist oxide of cobalt, the neutral muriate, or acid muriate of cobalt, as well as other salts of the same, are treated with dilute quadrisulphuret of lime, sulphurets of cobalt are formed in various proportions according to the ingredients, from the deutosulphuret to the dodecasulphuret: these precipitates are all black and not easily distinguished in appearance; but there is reason to believe they are true chemical compounds.
34. _Sulphurets of manganese._