350 JOSEPH STRUTHERS 



fied with beds of clay or rock, but they often occur as what 

 are known as hving beds, in which the sulphur is continuously 

 being formed as the result of active chemical decompositions. 

 In such a living sulphur bed the sulphur is produced by the 

 direct action of sulphurous gases, especially hydrogen sulphide 

 (HsS) and sulphur dioxide (SO3), which in the presence of mois- 

 ture (H3O) react and form water (H3O) and sulphur (S) . These 

 gases emanate in regions of active or expiring volcanoes, and 

 form the so called solfataras, in which the sulphur has been 

 condensed from the vapors formed and has collected in cracks 

 in the lava and tuffs or in the kaolin or clay formed by the 

 corroding action of the acid vapors on the lavas. 



From a commercial standpoint, especially for the manu- 

 facture of sulphuric acid, the mineral from the solfatara de- 

 posits is not regarded favorably on account of its liabihty to 

 contain arsenic in the form of the minerals orpiment (AS3S3) 

 and realgar (AsS). Sulphur of this character has been im- 

 ported from the island of Vulcano, one of the Lipari group, off 

 the coast of Italy. A similar association of arsenic minerals 

 has been reported in the sulphur deposits in Yellowstone na- 

 tional park. 



Traces of selenium and tellurium, which are also objec- 

 tionable in the manufacture of sulphuric acid, occur in the 

 volcanic sulphur deposits in Japan. The only solfatara de- 

 posits of commercial importance at the present time are in 

 southern Utah and in the island of Hokkaido, Japan. 



The world's supply of sulphur is derived from two prin- 

 cipal sources: (1) The deposits of the native mineral sulphur 

 which yield the sulphur or brimstone of commerce; and (2) 

 the deposits of the sulphide minerals — ^pyrite, pyrrhotite, chal- 

 copyrite, sphalerite, and other sulphides — from which is de- 

 rived the sulphur dioxide gas used in the manufacture of sul- 

 phuric acid. In addition to these two natural sources of sul- 

 phur, there are several artificial products containing sulphur, 

 chiefly in the form of sulphur dioxide gas, in sufficient quan- 

 tity to admit of commercial utilization. There are also lead, 

 copper, and other mattes from the furnace treatment of va- 

 rious lead and copper ores and alkali waste from chemical 

 works engaged in manufacturing soda. 



