generated by dissolving granulated zinc in dilute sulphuric acid. All the different pieces of the apparatus were carefully weighed in the first place to enable me to determine what might be driven off, or what addition might be made to the substances operated on during the process.

Experiments with a Mixture of Sulphuret of Antimony and Oxide of Antimony.

Antimonious acid prepared from subantimonite of potash (crocus antimonii elota) by digestion in nitric acid, was mixed by trituration with its own weight of metallic antimony in fine powder, and put into a glass globular vessel blown by the lamp, having a capacity of fully a cubic inch, the mouth of which was afterwards drawn out into a capillary tube. This glass vessel was put into a crucible, and was raised to a red heat, which was kept up about ten minutes. When the glass was broken in pieces, there was found in its upper part white or yellowish-white crystals, of two different forms; namely, octahedrons and prismatic needles. The mass found at the bottom consisted of a metalline regulus lying undermost, and over it an oxide consisting of a fused yellow-grey mass, having a crystallized fracture, and containing drusy cavities, lined with white, short, needleshaped crystals. Sulphuret of antimony was prepared from this regulus by mixing it with 40 per cent. of pure native sulphur, and heating it in a little glass globular vessel. It was crystallized, and all excess of sulphur had been driven off by heat.'

The purest portions of the oxide thus obtained were pulve rised, and exactly mixed with the sulphuret of antimony, accord ing to the proportions which Berzelius has given for the constitution of red ore of antimony (Rothspeissglanserz), Sb + 2 Sb, S3; namely, 100 parts sulphuret with 43-2 parts of oxide.. A quantity of this mixture was put into a glass globe blown by the: lamp. This quantity after being gently heated weighed 2·335, grammes. The glass was exposed to the flame of a spirit-lamp and as soon as the mixture became fully red-hot, it melted,, and was found after cooling still to weigh exactly 2-335 grammes. The product of this operation was a glass having the metallic lustre and a dark steel-grey colour with a shade of red, very similar to the dark variety of red ore of antimony. It appeared opaque, except those portions which had formed a thin crust on. the inside of the glass. These were translucent, and had a yel-lowish-red colour. When reduced to powder, it had a dark reddish-brown colour. As the weight was not altered, by the fusion, it is obvious that it had lost no sulphur nor oxygen during the process.

A portion of the powder of this crocus, or compound of sulphuret and oxide of antimony, was put into the part of the apparatus marked E, which, after being gently heated, weighed

1.27 gramme. The caoutchouc tube was now fixed on, and all the other parts of the apparatus were adjusted to their places. After the hydrogen gas had passed over a good while, and the whole atmospherical air had been driven out of the tube, the powder was gradually heated by means of a spirit-lamp. Water began very quickly to be formed, and was deposited in the form of vapour on the sides of the glass globe. When the hydrogen gas passed over briskly, the aqueous vapour was carried off by the current, and was naturally absorbed by the chloride of calcium in G; but when the hydrogen gas passed over slowly, or only at intervals, the water collected in drops in the pipe. After the process had continued two or three hours, the antimoniacal mass had in part passed through the glass globe, and a little sulphur began to appear on its outside. The fire was of necessity withdrawn, and the process stopped. During the whole continuance of the operation sulphuretted hydrogen gas was disengaged, and conducted by means of the crooked tube into a glass containing liquid ammonia in order to prevent it from making its way into the room. Into the tube beyond the glass globe, 0.04 gramme of water had condensed, and the tube containing the chloride of calcium had increased considerably in weight. But it is needless to state this increase, because the portion of the chloride nearest the ammoniacal water had deliquesced in consequence of the evaporation of a portion of that liquid into it. The residual matter in E weighed 1·005; and consequently it had lost in oxygen and sulphur 0.265 gr. It consisted of a multitude of small metallic reguli, and of a brassyellow crystallized sublimate, which seemed to have the octahedral form. There was also a little sublimate in the tube, which had more of the metallic lustre, and was more shining, and which probably was merely sulphuret of antimony. The yellow crystallized substance dissolved with ease in aqua regia, and seemed to consist chiefly of sulphur.

Decomposition of Red Silver Ore by Hydrogen Gas.

When it was thus ascertained that hydrogen gas is capable of reducing oxide of antimony from its combination with sulphuret of antimony, the same process was undertaken with red silver ore, and at the same time measures were taken to collect and decompose all the sulphuretted hydrogen formed during the process, that the quantity of sulphur in the ore might be likewise determined. For this purpose a somewhat concentrated solution of sulphate of copper was prepared, and a portion of it (previously deprived of its atmospherical air by boiling) was put into two phials; and another portion supersaturated with ammonia, so that a clear solution was obtained, was put into two other phials. A new portion of chloride of calcium was put into the tube G, and its weight was again determined, and from

it there was a communication by means of glass tubes with the phials holding the solution of sulphate of copper. These again communicated with the ammoniacal solution of copper in the other two phials, by means of glass tubes passing through corks in the mouths of the phials, precisely as in a common set of Woulfe's bottles. Into the glass globe E, a quantity of pulverised red silver ore was put, which, after having been gently heated, weighed 1·504 gramme. Then the whole apparatus was put in its place.

When the evolution of the gas had continued for half an hour, and the atmospherical air had been expelled, a spirit-lamp was applied to the ball E, and a stream of gas was made to pass equably and slowly. On the first application of the heat, a light coloured smoke appeared, and passed over into the pipe from E, but it vanished immediately, and left no trace behind it. Sulphuretted hydrogen gas was immediately formed, and instantly rendered the first phial turbid. Soon after a deposit began to appear in the second, then in the third, and at last even some deposit appeared in the fourth phial. In the ball and tube not the least trace of water made its appearance, and indeed nothing whatever but an exceedingly small quantity of smokelike matter. After the heat had been continued without interruption for eight hours, the mineral had assumed the form of a metallic regulus, which easily melted by the heat of the spiritlamp. And in the throat, and tube of the little apparatus È, an inconsiderable quantity of a greyish matter with the metallic lustre had sublimed. When the hydrogen gas ceased to be sulphureous, and the mineral to diminish any more, the gas was still allowed to pass for some time. The lamp was then put out, and the apparatus taken to pieces. The residue in the retort was found to weigh 1-2365 gr. The glass ball was broken, and the regulus taken out; it weighed 1.2255 gr. It had externally the metallic lustre ; but was here and there covered with a little black powder; but its quantity was so small that it could not be separated. Probably it was nothing else than small reguli in very fine mechanical division. The tube beyond the glass ball, though it contained the smoke-like matter, was not sensibly increased in weight. The chloride of calcium had become heavier by 0.010 gr. and it was observed that the parti cles of salt were a little soiled by a fine brownish-grey matter. The hydrogen had taken from the mineral 1.5041-2365 = 0.2675 gramme, which amounts to 17.785 per cent.

A set of experiments was now undertaken on the regulus, which exhibited all the characters of an alloy of silver and antimony. The object in view was to remove the antimony by cupellation, and leave the silver. But in the first place a set of experiments was made upon an artificial mixture of silver and antimony.

New Series, VOL. VIII.

D

Experiments to separate Antimony from Silver by Cupellation.

Of this alloy, which was so formed as to contain about 31 per cent. of antimony, and which in its fracture and aspect perfectly resembled the regulus obtained from red silver ore, 0.738 gr. was placed in a bone-earth cupel, which was introduced into a red-hot muffle in a cupellating furnace. The heat in the muffle was increased by means of an air tube introduced into the muffle through a piece of charcoal placed in its mouth. The antimony was speedily driven off, and in great quantity; and when on increasing the heat, and blowing on the cupel with a bellows, no more antimonial fumes appeared, the silver regulus was withdrawn, and found to weigh 0.512 gr. It was ductile, and on the surface dull and greyish, showing that it was not quite free from antimony. It was, therefore, enveloped in five times its weight of pure lead, and exposed to the usual cupellating process till it assumed the appearance of pure silver. The regulus now obtained was silver-white, had a strong metallic lustre, and weighed 0.507 gr. It amounted, therefore, to 68 per cent. of the antimonial alloy; and the regulus first obtained contained about 1 per cent. of antimony. An experiment was made with another portion of the same alloy. It gave, after the first process, a dull regulus, whose weight was very nearly in the same proportion as in the experiment already described; and when it was dissolved in nitric acid, it left behind it a little oxide of antimony. The pure regulus obtained in the first experiment dissolved in that acid without leaving any residue what

ever.

After these preliminary trials, 0.511 gr. of the regulus obtained from red silver ore was taken and treated in precisely the same way. The first process gave a regulus weighing 0.375 gr. dull, and with a yellowish-grey colour on the surface; and when it was cupellated with five times its weight of lead, it became silver-white and splendid, and weighed 0-370 gramme. It dissolved in nitric acid without any residue whatever, and gave with muriatic acid horn silver, weighing after fusion 0.490 gramme, equivalent to 0.369 silver, and thus corresponding very nearly with the original weight of the regulus. According to this experiment, the whole regulus, weighing 1-2255 gramme, contained 0.8866 gramme silver, and the antimony driven off weighed 0-3389 gramme.

The matter which had passed into the tube E weighed, as has been already mentioned, 0·011 gramme. The fragments of the glass to which that grey metallic-looking substance adhered, were digested in nitric acid, which dissolved a little sulphur, as was evident from the action of muriate of barytes on the liquid. What remained was dissolved in muriatic acid, and contained, as far as so small a quantity of matter could be tested, nothing

else than antimony. The sublimate, therefore, consisted of sulphuret of antimony. Its weight (determined by weighing the glass fragments before and after the digestion in the acids) was 0.0065 gramme. It consisted of course of 0.0047 antimony and 0.0018 sulphur. When we subtract this 0.0065 from the 0-011 (the total weight), there remain 0.0045, which consisted of a brown-coloured earthy matter, but too small in quantity to be submitted to any tests to determine its nature.

The sulphuret of copper which had precipitated in the different phials was collected on a filter, and well washed with water. It was then dissolved in aqua regia, which, after long digestion, left a light-yellow powder, consisting of sulphur. It weighed, when well dried, 0·106 gramme, and burnt easily, leaving a blackgreyish residual matter, weighing scarcely a milligramme. The solution in aqua regia was precipitated warm by muriate of barytes. The sulphate of barytes obtained weighed 1.04 gramme, equivalent to 0.143 gramme sulphur. Thus the whole quantity of sulphur amounted to 0.248 gramme. The matter deposited on the chloride of calcium might also contain a little sulphur, left on it by the warm sulphuretted hydrogen gas; but it is impossible to determine its amount with accuracy.

The preceding analysis of red silver ore gives us the following constituents:

If we examine this mineral in a theoretic point of view, we find that 58.949 silver combine with 876 sulphur; and that 22.846 of antimony unite with 8.549 sulphur. We see further that the sulphuret of silver is a compound of 1 atom silver and 2 atoms sulphur; while the sulphuret of antimony consists of 3 atoms sulphur and 1 atom antimony. The chemical formula for red silver ore, therefore, must be, 3 Ag S2 + 2 Sb S3, which gives us its constituents as follows:

To explain the composition of red silver ore to the English readers, it will be merely necessary to substitute the atomic