hydroguret of antimony thus formed, is separated by the addition of acid, which unites with the alkali.

Remark. Other preparations of antimony as the muriate, supertartrite of potash and antimony, &c. will be noticed under the Salts of Antimony. The following, however, may be noticed here. To prepare cinnabar of antimony:

Experiment 20. Pulverise one part of sulphuret of antimony and three of oxygenated muriate of mercury, according to Baume; but according to Fourcroy, one part of the former to two of the latter: mix these substances, and proceed in other respects as in the preceding operation. When the distillation is finished, adapt another receiver to the retort, and sublime the residuum with a strong heat. A substance will be obtained in the form of red needles, called cinnabar of antimony.

This is the effect of a double affinity. The sulphuret of antimony exchanges its sulphur for the acid given up by the oxygenated muriate of mercury.

The combination of antimony with other metals is not attended with any difficulty.

Antimony combines with most of the metals; but the alloys so formed, are of little or no importance, if we except one or two, such as that of type metal and of music plates.

SECTION XVIII.

OF TELLURIUM.

Experiment 1. Tellurium is obtained, according to Klaproth, by forming oxyd of tellurium into a paste, with a few drops of linseed oil, and then putting it into a small glass retort, or crucible. As the oil becomes decomposed, brilliant and metallic drops are observed on the upper part of the vessel, which increase in number until the oxyd is revived.

The process for obtaining oxyd of tellurium may be seen in the following analysis of tellurium.

Experiment 2. Let the white gold ore be gently heated with six parts of muriatic acid; three parts of the nitric being then added, the mixture is boiled, upon which there arises a considerable effervescence, and a complete solution is obtained. The filtered solution must be diluted with as much water as it can bear without becoming turbid, which is a very small quantity; and a solution of potash is then to be added to the liquor, until the white precipitate, which is at first formed, disappears, and nothing remains but a brown flaky sediment, which is the oxyd of gold mixed with the oxyd of iron contained in the ore. This may be dissolved in nitro-muriatic acid; and the gold be precipitated by a solution of nitrate of mercury, and then the iron by potash. Muriatic acid Muriatic acid is then added to the before obtained alkaline solution, in sufficient quantity to saturate the potash. An excess of the acid must be avoided. A white precipitate is thus produced in great abundance. This, when washed, is the oxyd of tellurium.

Remark. Tellurium is a new metal discovered by Klaproth, in the year 1797. It is found in three different ores; namely, 1. In the white gold ore of Fatzebay, formerly named aurum paradoxum, found in the mine called Maria-hilf, in the mountains of Fatzebay, in Transylvania. In this ore tellurium exists alloyed with gold and iron. Its colour is between tin-white and lead-gray. It is in general found massive. The texture of this ore is granular, and its lustré considerably metallic. 2. In the graphic gold ore, (aurum graphicum) of Offenbanya, it is alloyed with gold and silver. This ore is composed of flat prismatic crystals, the arrangement of which has some resemblance to Turkish letters; hence the name of the ore. It has a metallic lustre, and a tin-white colour, with a tinge of brassyellow. 3. It exists also in the ore known under the name of the yellow foliated gold ore of Nagzag; alloyed with gold, lead, silver, copper, and sulphur. This

will be left, which is the per oxyd or arsenic acid. See Arsenic Acid.

Experiment 10. If one part of arsenic and four or five of sulphur be hastily melted together in a well closed crucible, a compound of a yellow colour, called sulphuret of arsenic will be formed.

Experiment 11. Put equal quantities of arsenic, reduced to powder, and phosphorus, into a Florence flask; pour water upon them, so as to cover them an inch, and apply the gentle heat of a lamp. The arsenic and phosphorus will unite, and form a phosphuret of that metal.

This combination may likewise be conveniently effected by gently heating, in a close phial, equal parts of phosphorus and pulverised arsenic.

Experiment 12. If zinc and arsenic be put into a flask, and diluted sulphuric acid added, the arseniuretted hydrogen gas will be formed. See the Preparation of Arseniuretted Hydrogen Gas.

Arsenic unites with most metals, and its presence is detected by the appearance it gives to copper, in the following manner:

Experiment 13.

Insert a little arsenic, reduced to fine powder, between two polished plates of copper; bind them closely together with iron wire, and heat them. The inner surfaces of the copper plates will be rendered white by the arsenic.

The union of arsenic with copper may likewise be effected by fusing one part of arsenic and four of copper, in a common crucible. This alloy has received the name of white copper or white tombac. The alloy of tin and arsenic may be made in the following man

ner:

Experiment 14. Put into a crucible placed in a fire seven parts of tin, and one of arsenic; melt the mixture, and when completely united pour it out into an ingot. The alloy obtained will be found to be of a white colour; it is much harder, more sonorous, and less fusible than tin.

SECTION XX.

OF COBALT.

Experiment 1. The process made use of by chemists for obtaining cobalt, is to torrify the cobalt ore in an open fire, in order to separate from it the arsenic or sulphur. The cobalt is then obtained in the state of a black oxyd more or less dark. This oxyd must be mixed with three parts of black fiux, and one of decrepitated muriate of soda; some add also half a part of resin. The whole is put into a crucible of such a capacity that at least one-third of it may remain empty, and placed in a furnace exposed to a gentle heat until the resin ceases to burn; the fire must then be raised gradually, in order to bring the crucible to a white heat, and in that state it must be kept until the matters are completely fused. It is then suffered to cool, and having broken the crucible, the cobalt must be separated from the scoria, which are of a blue colour.

As cobalt thus obtained is always more or less impure (generally contaminated with iron) in order to get rid of the impurities, and particularly the iron, the following process is employed:

པསམ་ པའyuaས_b The solution must then

to be dissolved in nitric acid. be evaporated to dryness, and the remainder exposed for some time to a red-heat, whereby the nitrated iron becomes decomposed: or the solution of cobalt in nitric acid may be precipitated by pure potash. The precipitate after being washed is dissolved in nitric acid. This solution must be evaporated to dryness, and redissolved in as little distilled water as possible, and then precipitated by liquid ammonia. More ammonia is then to be added, in order to re-dissolve the precipitate. This ammoniacal solution must be evaporated to dryness, and then mixed with two parts of black flux into a paste with a sufficient quantity of oil, and ex

posed to a white heat in a forge for at least two hours. A button will thus be obtained which is pure cobalt.

If the ore of cobalt can not be had, the metal may be obtained from smalt (which is glass coloured with that metal) in the following manner:

Experiment 3. Take an ounce of best smalt, and` fuse it in a crucible with 8 ounces of dried soda, and the cobalt will be set at liberty. The alkali or rather silicated alkali which is formed, may be washed off.

Remark. Cobalt is of a gray colour, brittle, easily pulverisable, and melts at 130° Wedgwood. Its specific gravity is about 7.7.

Experiment 4. If cobalt be kept red hot in an open vessel, it is gradually converted into a powder at first blue, and at last becomes very dark.

Remark. It is hardly necessary to add, that this effect is owing to the absorption of oxygen. Cobalt is capable of combining with three doses of oxygen.

Experiment 5. If cobalt be dissolved in nitric acid and precipitated by potash, the prot oxyd will be formed.

Experiment 6. If this oxyd be exposed to the air it gradually absorbs oxygen, and is converted into the deut oxyd.

Experiment 7. If this be heated in the open air, it then the per oxyd. dually becoming black, and is Experiment 8. If oxyd of cobalt and sulphur be heated together, the sulphuret of cobalt will be formed.

Experiment 9. If cobalt be heated red hot in a crucible, and small pieces of phosphorus gradually dropt in, the phosphuret of cobalt will be the result.

The solution of cobalt in acids forms sympathetic inks. The muriate of cobalt, or green sympathetic ink, is made in the following way:

Experiment 10. Put into a mattrass one part of cobalt and four of nitric acid. Digest the mixture on a sand-bath for three or four hours, or until the solution be almost completed; then add muriate of soda equal in quantity to the cobalt employed, and four times as