Sulphuretted Hydrogen

(sül-fu-rět'ted,) or HYDROSULPHURIC ACID. (Chem.) This acid (HS) is a product of the putrefaction of organic substances containing sulphur, and is one of the causes of the sickening smell of drains, . Eggs, which contain a considerable proportion of sulphur, evolve S. H. as soon as they begin to change, and hence the a ociation between this gas and the " smell of rotten eggs." The same smell is observed when a kettle boils over upon a coke or coal fire, the hydrogen liberated from the water combining with the sulphur present in the fuel. Hydro - sulphuric acid is readily formed by heating a damp mixture of sulphur and wood charcoal, and may be obtained in large quantity by heating a mixture of equal weights of sulphur and tallow, the latter furnishing the hydrogen. This gas is at once distinguished from all others by its disgusting odor. It is one-fifth heavier than air (sp. gr. 1-1912). Its gaseous state is not permanent, but a pre ure of 17 atmospheres is required to reduce it to a colorle liquid, which congeals toa transparent solid at -122° F. Water absorbs about three times its volume of S. H. at the ordinary temperature; both the gas and its solution are feebly acid to red litmus-paper. The gas is very combustible, burning with a blue flame like that of sulphur, and yielding, as the chief products, water and sulphurous acid. This combustibility of S. H. is of the greatest importance in those proce es of chemical manufacture in which this gas is evolved (as in the preparation of ammoniacal salts from gas liquors), enabling it to be disposed of in the furnace instead of becoming a nuisance to the neighborhood. The gas causes fainting when inhaled in large quantity, and appears much to depre the vital energy when breathed for any length of time even in a diluted state. In its action upon the metals and their oxides, it resembles hydrochloric acid and the other hydrogen acids. [s. 866]