SULPHUR. 159 



gas is therefore imperfectly known. Its principal com- 

 pounds, are hydrofluoric acid, and fluor spar, to be here- 

 after described.* 



S.ULPHUR. 



381. DESCRIPTION. Sulphur is a brittle 



W/iatissul- 



phur? Where yellow solid, burning with a peculiar odor, 

 it occur? ma( j e familiar in the ignition of common 

 friction matches. With the metals, it forms sulphides 

 or sulphurets. In Sicily, and certain other volcanic 

 regions, it occurs in beautiful, yellow crystals. Gyp- 

 sum, and iron pyrites, or fools gold, represent the two 

 principal classes of minerals that contain it. It also 

 enters in small proportion into the composition of all 

 animal and vegetable substances. It is the sulphur in 

 eggs that blackens the silver spoon with which they are 

 eaten. 



382. PREPARATION. In preparing com- 



Describe the 



manufacture mercial sulphur, the impure material of 

 of suphur ? vo i can i c regions, is highly heated, and thus 

 made to fly off as vapor, leaving its earthy impurities 

 behind. The vapors are condensed as flowers of 

 sulphur. The process by which a solid is thus vap- 

 orized, and re-converted into a solid, is called sublima- 

 tion. Native sulphur may also be partially purified by 

 simple fusion. Its earthy impurities having settled, 

 it is poured off into moulds, and thus converted into 

 roll brimstone. 



* Many compounds of chlorine, bromine, iodine and fluorine, with 

 each other and with oxygen, are known to the chemist,/but they are 

 without interest to the general student 



V 



