HYDROGEN AND SULPHUR. 403 



composed by that metal, which has a strong affinity for sulphur, 

 and hydrogen is liberated, without any change of volume. The 

 reaction between hydrochloric acid and sulphuret of antimony 

 may be thus expressed : 



3H Cl and Sb S 3 == 3H S and Sb C1 3 . 



Properties. Sulphuretted hydrogen is a colourless gas, of a 

 strong and very disagreeable odour. Its density is 1191.2, by 

 the experiments of Gay-Lussac and Thenard. It consists of 

 2 volumes of hydrogen and l-3rd vol. of sulphur vapour, con- 

 densed into 2 vols., which form its combining measure. By a 

 pressure of 17 atmospheres at 50, it is condensed into a highly 

 limpid, colourless liquid, of sp. gr. 0.9, which is of peculiar inte- 

 rest as the analogue of water in the sulphur series of compounds. 

 The solvent powers of this liquid have not been examined. 

 The air of a chamber slightly impregnated by this gas may be 

 respired without injury, but a small quantity of the undiluted 

 gas inspired occasions syncope, and its respiration, in a very 

 moderate proportion, was found by Thenard to prove fatal 

 birds perishing in air containing 1-1 500th, and a dog, in air con- 

 taining 1 -800th part of this gas. Water dissolves, at 64, 2i 

 volumes of this gas, and alcohol, 6 volumes. These solutions 

 soon become milky, when exposed to air, the oxygen of which 

 combines with the hydrogen of the gas, and precipitates the 

 sulphur. Those mineral waters termed sulphureous, contain 

 this gas, although rarely in a proportion exceeding lj per cent 

 of their volume. They are easily recognised by their odour, 

 and by blackening silver. 



Sulphuretted hydrogen is highly combustible, and burns with 

 a pale blue flame, producing water and sulphurous acid, and 

 generally a deposit of sulphur when oxygen is not present in 

 excess. A little strong nitric acid thrown into a bottle of this 

 gas, occasions the immediate oxidation of its hydrogen, and often 

 a slight explosion with flame, when the escape of the vapour is 

 impeded by closing the mouth of the bottle by the finger. Sul- 

 phuretted hydrogen is immediately decomposed by chlorine, 

 bromine and iodine, which assume its hydrogen ; the odour of 

 sulphuretted hydrogen in a room is soon destroyed, on diffusing 

 a little chlorine through it. Tin and many other metals, heated 

 in this gas, combine with its sulphur with flame, and liberate an 

 equal volume of hydrogen. Potassium decomposes one moiety 



D D 2 



