SECT. in. ITS DESTRUCTIVE DISTILLATION. 127 



the world for ages. In 1861 no less than 42,000,000 

 gallons of petroleum were sent to England. The wells 

 are not without danger, for when they pass through]? 

 the coal strata, the petroleum is accompanied by aj 

 highly inflammable gas which on one occasion was 

 accidentally set on fire ; it ignited the petroleum, which 

 was forced out as from the mouth of a volcano, and 

 covered the ground with liquid fire far around ; at the 

 same time the burning gas formed an incandescent 

 atmosphere which extended to a still greater distance. 



The distillation of petroleum yields substances for the 

 most part identical with those arising from the distil- 

 lation of coal. The crude petroleum is put into an iron 

 retort connected with a coil of iron pipes surrounded by 

 cold water, called the condenser. Heat is applied to 

 the retort, and from the open extremity of the conden- 

 ser, a pale coloured liquid with a strong smell flows, 

 which is very volatile and explosive naphtha. After 

 the naphtha has passed over, an oil of excellent illumi- 

 nating quality is distilled over. Steam is then forced 

 into the retort, and a heavy oil is driven over, and 

 there remains a black, oily, tarry matter, and a black 

 cake used for fuel. After the naphtha has been 

 repeatedly distilled, benzol is formed, and when the 

 heavy oil is cooled to 30 Fahr., crystals of paraffin 

 appear, which are separated from the oil by pressure, 

 and when they are purified by alternate pressure and 

 agitation in a melted state, they are moulded into 

 candles. This paraffin is identical with that from coal. 

 Among the products of the distillation of petroleum arc 

 naphthalin whence aniline is obtained, which yields 

 mauve, magenta, and the other coal tar colours, also 

 solferino which yields dianthine and other dyes and has 

 been proposed as a substitute for chloroform and ether. 

 Many other substances have been separated from petro- 

 leum which like some from coal have not yet been 



