HYPOSULPHUROUS ACID as yet is only known in a state of combination with bases; for on attempting to separate the acid from the base, the former becomes deem posed into sulphur and sulphurous acid. The most important of its salts is the hypo .sulphite of soda 5Aq), whose mode of preparation and characters are described in the articl.' Somum. This and other soluble hyposulphites may be easily recognized by the facility with which they dissolve the haloid salts of silver, forming a solution of an extremely sweet taste, and containing a double hyposulphite of silver and soda, with an admixture of chloride, iodide, or bromide of sodium. It is this power of dissolving those salts of silver which arc insoluble in water, that renders the hyposulphite of soda so important an agent in photography. The only other salt of this acid which we shalt notice is the hyposulphite of gold and soda (NaO, 4 Aq] which may be prepared by mixing concentrated solutions of 1 part of chloride of gold and 3 parts of hyposulphite of soda, and adding alcohol, when the required salt is precipitated. It is used for gilding the daguerreotype plate, and for coloring the positive proof obtained in photographic printing.
With hydrogen, sulphur forms two compounds, viz. sulphureted hydrogen, or sulphuric acid (q.v.), and persulphide of hydrogen, an oily liquid, having the smell and taste of sulphureted hydrogen, and in many of its properties having an analogy to binoxide of hydrogen. Sulphur combines with carbon to form a bisulphide of carbon (CS2), a very volatile colorless liquid, of a high refractive power, of an acrid and pungent taste, and a very disagreeable odor. It is heavier than water, in which it is insoluble, but dissolves freely in alcohol and ether, and is the best solvent for sulphur and phos phorus. Bisulphide of carbon does not occur as a natural product, but may be ob tained by heating fragments of charcoal to bright redness in a porcelain tube, and passing sulphur vapor along it. Its vapor, when freely inhaled, exerts a similar anes thetic action with those of chloroform and ether. Workmen in caoutchouc or other
manufactures in which bisulphide of carbon is used as a solvent, suffer very much from prolonged exposure to its vapor, which produces headache, loss of appetite, impair ment of vision and hearing, and causes general derangement of health by its deleterious action on the nervous system. Sulphur combines with chlorine iu several proportions, the most important of these compounds being subchloride of sulphur (S2CI) and the chloride of sulphur (SCI). Both of them are liquids, and are formed by the direct action of the combining elements. The subchloride is a yellow volatile liquid with a penetrating' and disagreeable odor. When dropped in water, it sinks to the bottom (its spec. gray. being about 1.657), and is slowly decomposed into hydrochloric and various sulphur acids, and free sulphur. It is capable of dissolving about 67 per cent of sulphur at an ordinary temperature, and, like bisulphide of carbon, is extensively employed in vulcanizing india-rubber. The chloride of sulphur is formed by saturating the subchloride with chlorine. It is a deep-red liquid, resembling the previous com pound in most of its properties. It is decomposed by the sun's rays into the subchloride and free chlorine.
With regard to the history of sulphur and its compounds, it may be observed that sulphur seems to have been known from the earliest times, and that sulphuric acid was most probably known to the Arabians. The manufacture of English sulphuric acid dates, however, only from the 1Sth century. Sulphurous acid was first investigated by Stahl, Scheele, and Priestely; hyposulphuric acid was discovered by Welter and Gay-Lussac; hyposulphurous acid, by Gay-Lussac and Herschel; trithionic acid, by Langlois; tetrathionic acid, by Fordos and Gelis; and peutathionic acid, by Wacken roder. Scheele was the first who accurately studied hydrosulphuric acid, or sulphur eted hydrogen.