Sulphides, Or Snlpbnrots, compounds in which sulphur forms the electro-negative element. Sulphur unites with all the metals, with most of the non-metallic elements, and with many organic radicals. The sulphides have generally a constitution corresponding to the oxides, and like them may be divided into acid and basic sulphides, which are capable of uniting and forming sulphur salts. Thus, we have stan-nate of potassium, K2Sn03, and also sulpho-stannate of potassium, K2SnS3. The sulphides are decomposed more or less perfectly by hy- -drochloric acid, and behave like the corresponding oxides, yielding one molecule of sulphy-dric acid for every molecule of sulphur in the sulphide. Thus, FeS + 2HCl = H2S + FeCl2; and SbS8 + 6HCI=3H2S + 2SbCl3. Of the sulphides of the non-metallic elements, those of carbon and chlorine are the most important. Bisulphide of carbon, carbon disulphide, or sulpho-carbonic acid, CS2, is the only sulphide of carbon which is positively known. It is prepared on a large scale as a solvent for various manufacturing purposes. A large earthen retort has a tube which passes through the mouth down to near the bottom.

The retort is filled with charcoal and heated to redness in a furnace, and bits of sulphur are dropped from time to time down the tube, which after each introduction is stopped with a cork. The neck of the retort is connected with a condensing tube, which is kept cold by a stream of water, and dips into a vessel of cold water. The sulphide which collects at the bottom of this vessel contains an excess of sulphur, from which it is freed by redistillation. By another process sulphur vapor is driven over red-hot coke. Sulphide of carbon is a colorless, mobile, highly refracting liquid, its index of refraction being 1.678. (See Light, vol. x., p. 439.) It has a peculiar, fetid, disagreeable, alliaceous odor, and when breathed produces great depression, followed by coma. The density of the liquid is 1.274, water=l; of the vapor, 2.67, air=l; boiling point, 118.4°. It freely dissolves sulphur, depositing it on evaporation in beautiful octahedral crystals. It also dissolves phosphorus, iodine, camphor, and caoutchouc, and mixes easily with oils. It is extensively used in the vulcanization of caoutchouc and the manufacture of gutta percha, for extracting bitumen from mineral substances, and of oil from seeds.

Sulphide of chlorine, S2CI2, is formed by passing dry chlorine over melted sulphur contained in a glass retort. A deep orange-yellow, mobile fluid distils over, having a peculiar disagreeable odor, boiling at 282° F.; sp. gr. 1.687. It dissolves sulphur in large quantities. Dissolved in crude benzole with excess of sulphur, it is also used in Europe for vulcanizing caoutchouc. The principal sulphides of organic radicals are of the alcoholic series, and form a class of ethers, as hydro-sulphuric ether, or monosulphide of ethvle, (C2H6)2S, and the disulphide,' (C2H5 )2S2. Sul-phydrate of ethyle, or mercaptan, C2II5SII, is interesting as being the sulphur analogue of common alcohol, or hvdrated oxide of ethvle, C2H5OH. (See Alcohol, and Etiiyle.) Mer-captan (mercurium captans, which signifies having a strong tendency to seize upon or combine with mercury) was discovered by Leise in 1833, and has since been examined by Liebig and others. It is a colorless mobile liquid, of an exceedingly offensive and permanent garlic odor; sp. gr. 0.842; boiling point about 144° F. When it is mixed with mercuric oxide, violent reaction ensues, with formation of water, and a white substance, soluble in alcohol, which by the action of sulphydric acid yields sulphide of mercury with reproduction of mercaptan.

A drop on the end of a glass rod waved through the air will evaporate so rapidly as to freeze a portion remaining. It forms an interesting class of compounds with other elements, for which the reader is referred to larger works on chemistry. The sulphides of methyle, (CH3)2S and (CH3)2S2, and also methyle sulphydrate, or methyle mercaptan, CH3SH, and other organic sulphides and sulphydrates, possess much chemical interest.