SULPHURETTED HYDROGEN 957 



becomes again perfectly liquid. When heated in contact with the air, sulphur ignites 

 and burns with a pale blue flame, generating sulphurous acid gas, which is employed 

 to bleach woollen and silken goods ; to disinfect vitiated air, though for this purpose 

 it is greatly inferior to chlorine ; to kill mites, moths, and other destructive insects 

 in zoological collections ; and to counteract too rapid fermentation in wine-vats, &c. 



Sulphur has a slight odour, and scarcely any taste. It is a very bad conductor of 

 heat ; and a lump of sulphur, even by the heat of the hand, will produce a crackling 

 sound, and often break in pieces. It is a bad conductor of electricity, and by friction 

 becomes strongly charged with electricity, which is of the negative kind. Sulphur 

 is insoluble in water and alcohol ; but is dissolved by oil of turpentine and the 

 fatty oils : the best solvent of it, however, is bisulphide of carbon. In its chemical 

 relations it is allied to oxygen, &c. It has been known from the most remote ages, 

 and from its kindling at a moderate temperature is employed for readily procuring 

 fire, and lighting by its flame other bodies less combustible. 



Sulphur is also employed for cementing iron bars into stones ; for taking impressions 

 from seals and cameos, for which purpose it is kept previously melted for some time 

 to give the casts an appearance of bronze. Its principal uses, however, are for the 

 manufactures of gunpowder and sulphuric acid. 



There is another form in which sulphur is sometimes known, and this is what is 

 termed horse brimstone or black sulphur. It is the dregs of the subliming pot after the 

 purification of sulplmr, and often contains large quantities of arsenic. 



The purity of sulphur may be known by its being completely volatilisable, and by 

 being soluble in bisulphide of carbon ; f t ny earthy impurities would in either case 

 remain behind. 



SUIiPHURATION is the process by which woollen, silk, and cotton goods are 

 exposed to the vapours of burning sulphur sulphurous acid gas. 



Sulphuring-roqms are sometimes constructed upon a great scale, in which blankets, 

 shawls, and woollen clothes may be suspended freely upon poles or cords. The floor 

 should be flagged with a sloping pavement, to favour the drainage of the water that 

 drops down from the moistened cloth. The iron or stoneware vessels, in which the 

 sulphur is burned, are set in the corners of the apartment. They should be increased 

 in number according to the dimensions of the place, and distributed uniformly over 

 it. The windows and the entrance door must be made to shut hermetically close. 

 In the lower part of the door there should be a small opening, with a sliding shutter, 

 which may be raised or lowered by the mechanism of a cord passing over a pulley. 



SULPHURETTED HYDROGEN, or Hydrosulphiiric acid. Sulphur does not 

 unite directly with hydrogen when in the free state, but when the sulphides of those 

 metals which dissolve in dilute acids with liberation of hydrogen are treated with the 

 same acids, they are dissolved, and the hydrogen, as soon as liberated, unites with the 

 sulphur of the sulphide, and is evolved as sulphuretted hydrogen. Sulphide of iron is 

 the most general substance that is used for this purpose ; the action goes on without 

 the application of heat. The following equation represents the decomposition : 



FeS + HO.S0 3 = FeO.SO 3 + HS (PeS + H-SO 1 = FeSO* + H 2 S). 



This substance does not yield the gas in the pure state ; hence, when its purity is 

 an object, it is obtained by the action of hydrochloric acid on tersulphide of antimony ; 

 in this case the gas is only liberated by the application of heat : 



SbS 3 + 3HC1 = SbCP + 3HS (Sb*S s + 6HC1 = Sb-Cl 6 + 3H 2 S). 



The sulphide of iron may easily be prepared by projecting into a red-hot crucible a 

 mixture of 2 parts of sulphur and 4 parts of iron-filings, or borings of cast iron, and 

 excluding the air as much as possible. Another process is to raise a bar of iron to a 

 white heat, and then rub it with a lump of sulphur, over a vessel of water, when the 

 drops of fused sulphide fall into the water. 



Sulphuretted hydrogen, at ordinary temperatures, is a colourless gas, possessing a 

 most disgusting odour. It is liberated by many vegetable and animal substances in a 

 state of decay. Its density is 1'171. and it contains 1 part of hydrogen and 16 parts 

 of sulphur by weight. It possesses the properties of an acid, and its solution in water 

 reddens litmus-paper. 



At a temperature of 50, and under a pressure of 17 atmospheres, it is condensed 

 to a highly limpid colourless liquid, of specific gravity 0'9, and when cooled to 122 

 solidifies, and is then a white crystalline translucent substance, heavier than the 

 liquid. In the undiluted state this gas is very suffocating : the best antidote is a little 

 chlorine, which decomposes it immediately, liberating the sulphur : 



HS + Cl = HC1 + S (H 2 S + Cl 3 = 2HC1 + S). 



It is very soluble in water, that liquid dissolving 2 times its bulk of the gas; the 



