SULPHUR AND ITS COMPOUNDS. 



33 



illuminating gas, produced from bituminous coal artifi- 

 cially, is produced naturally in many localities, and prob- 

 ably comes from the action of heat upon bituminous 

 coal, or some other substance of a kindred character. In 

 the village of Fredonia, New York, near Lake Erie, this 

 gas issues so abundantly from a slate rock that it is col- 

 lected, and is used by the inhabitants for lighting the 

 place. 



Fig. 19. 



CHAPTER IV. 



SULPHUR AND ITS COMPOUNDS. 



49. Native Sulphur. This substance is of a 

 pale yellow color. It is found both crystallized 

 and uncrystallized. Its crystallized 

 form is an octahedron, as seen in Fig. 

 1 9. When sulphur is melted, and then 

 left to crystallize, the crystal takes the 

 form seen in Fig. 20, which is very dif- 

 ferent from the forms which are as- 

 sumed in nature. Sulphur is often found in fis- 

 sures and cavities in lava. The most important 

 locality of sulphur is Sicily. Sixteen or seven- 

 teen thousand tons are imported annually into 

 England from Sicily, to say nothing of the sup- 

 ply to other countries. Much of the sulphur 

 of commerce is obtained from the sulphurets of iron and 

 copper. The sulphur is driven off from these ores by 

 heat, and is collected in brick chambers. It is one of the 

 ingredients of gunpowder, and is used in bleaching and 

 in the manufacture of sulphuric acid, as described in 

 249, Part II. 



50. Sulphurets of Iron. The bisulphuret of iron is one 

 of the most common ores in the earth, and has been known 

 from ancient times, when it received the name of pyrites, 

 from the Greek word pur, fire, because, as Pliny says, 



B2 



Fig. 20. 



