SULPHUR. 



379 



potassium with sulphuric acid. It is a deadly poison, and found in peach- 

 stones. Free cyanogen is a gas. The bisulphide of carbon is a colourless, 

 transparent liquid. It will easily dissolve sulphur and phosphorus and 

 several resins. When phosphorus is dissolved in it, it makes a very danger- 

 ous " fire," and one difficult to extinguish. We must now leave carbon and 

 its combinations, and come to sulphur. 



SULPHUR is found in a native state in Sicily and many other localities 

 which are volcanic. It is a yellow, solid body, and as it is never perfectly 

 free from earthy matter, it must be purified before it can be used. It 

 possesses neither taste nor smell, and is insoluble in water. Sulphur is 

 purified in a retort, C D, which communicates with a brick chamber, A. The 



Fig. 382. Sulphur ftirnace. 



retort is placed over a furnace, K, and the vapour passes into the chimney 

 through the tube, D, where it condenses into fine powder called " flowers of 

 sulphur" (brimstone). A valve permits the heated air to pass off, while 

 no exterior air can pass in, for explosions would take place were the heated 

 vapour to meet the atmospheric air. The danger is avoided by putting an 

 air reservoir outside the chimney which is heated by the furnace. The 

 sulphur is drawn out through the ap^ :ure, r, when deposited on the floor of 

 the chamber. The sulphur is cast into cylinders and sold. Sulphur is 

 soluble in bisulphide of carbon, and is used as a medical agent. 



The compounds of sulphurs with oxygen form an interesting series. 

 There are two anhydrous oxides (anhydrides), viz., sulphurous and sulphuric 

 anhydride (SO 2 and SO 3 ). There are two notable acids formed by the 



