SULPHITES 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 sul- phide which collects at the bottom of this ves- sel contains an excess of sulphur, from which it is freed by redistillation. By another pro- cess 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 =1 ; of the vapor, 2'67, air=l ; boiling point, 118'4. It freely dissolves sul- phur, depositing it on evaporation in beauti- ful octahedral crystals. It also dissolves phos- phorus, 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, S 2 C1 2 , is formed by passing dry chlorine over melted sulphur contained in a glass retort. A deep orange-yellow, mobile fluid distils over, hav- ing 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 sul- phides of organic radicals are of the alcoholic series, and form a class of ethers, as hydro- sulphuric ether, or monosulphide of ethyle, (C 2 H 6 ) 2 S, and the disulphide, (C 2 H 6 ) 2 S 2 . Sul- phydrate of ethyle, or mercaptan, C 2 H 6 SH, is interesting as being the sulphur analogue of common alcohol, or hydrated oxide of ethyle, CaHsOH. (See ALCOHOL, and ETHYLE.) Mer- captan {mer curium captans, which signifies having a strong tendency to seize upon or com- bine 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 alco- hol, 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 re- ferred to larger works on chemistry. The sul- phides of methyle, (CH 3 ) 2 S and (CH 3 ) 2 S 2 , and also methyle sulphydrate, or methyle mercap- tan, CHsSH, and other organic sulphides and sulphydrates, possess much chemical interest. SULPHITES, salts formed by the union of sul- phurous acid with bases, or more strictly speak- ing by the action of sulphurous acid on bases ; SULPHUR 455 the two atoms of hydrogen in the molecule of the acid being partially or wholly replaced by a metallic basyle or a radical, forming normal and acid salts. (See SALTS.) Thus, normal sulphite of potassium, K 2 S0 3 , may be formed by wholly replacing the hydrogen in the acid, H 2 S0 3 ; or the acid sulphite, KHSOs, may be formed by employing half the quantity of acid. The sulphites of the metals are usually formed by passing -sulphurous anhydride, S0 2 , through aqueous solutions or mixtures of hydrates or carbonates, the anhydride being first converted into the acid by combining with the elements of water, whereupon double decomposition immediately takes place, with an exchange between the metallic basyle and the hydrogen constituent of the acid. Sulphurous acid com- bines with nearly all the metals, the most im- portant sulphites being those of calcium and sodium. Sulphite of calcium may be precipi- tated in an anhydrous state by passing sul- phurous anhydride through water having hy- drate of lime in suspension, or through a solu- tion of chloride of calcium. It is manufac- tured on a large scale and used in bleaching, and for protecting organic substances from decay. The sulphites of sodium comprise a normal salt, Na 2 S0 3 , and an acid salt, NaHSOs. The normal salt is prepared by saturating a solution of carbonate of soda with sulphurous acid and adding to it as much carbonate of soda as it originally contained while warm. On cooling, the salt separates in monoclinic crystals, having seven molecules of water of crystallization (Na 2 S0 3 + 7H 2 0). Another hy- drate was formed by Muspratt, containing ten molecules of water. The acid sulphite is pre- pared by supersaturating the solution of sodic carbonate with sulphurous acid. Both of these salts have been used to remove the traces of chlorine in paper pulp, under the name of anti- chlor, but they have been partially superseded by hyposulphite of sodium, or this salt is used in connection with them. (See PAPER.) The two atoms of hydrogen in the molecule of sul- phurous acid may be partly or wholly replaced by monatomic alcohol radicals, forming acid and neutral sulphurous ethers, the acid ethers being sometimes called sulpho-acids. Ethyl- sulphurous acid, (C 2 H 8 )HS0 3 , is formed by the action of nitric acid on sulphydrate of ethyle or mercaptan, (C 2 H 5 )HS. Neutral sulphurous ether, (C 2 H 6 )2S0 3 , may be formed, among other methods, by the action of absolute alcohol on disulphide of chlorine. The alcoholic sulphites and other sulpho-ethers and compounds have been carefully studied by Muspratt, Gerhardt, Eammelsberg, Kolbe, and others. They form an extensive and interesting series. SULPHUR, an elementary substance belonging to the class of metalloids. It has been known from the earliest times as the sublimed product of volcanoes, and as a natural mineral deposit in clay and marl strata in tertiary formations, and is also associated with gypsum, being one of the sources of this mineral. (See GYPSUM.)
