CONSTITUENTS OP PLANTS, ETC. 



323 



Fig. 110. A View on Oil Creek, Penu., showing Oil- Wells, Derricks, etc. 



ground and ran along the surface might be obtained in 

 great quantity by digging down to its source. His expec- 

 tations were more than realized ; and a well which yielded 

 400 gallons of oil a day, worth at the time 55 cents per 

 gallon, rewarded his exertions, and successfully answered 

 the ridicule of his neighbors. The eleven years succeeding 

 this discovery produced more than thirty-five million bar- 

 rels of this useful article. 



443. Composition of Petroleum. Petroleum is a mixture 

 of a great number of hydrocarbons, differing from each 

 other in volatility and density. These hydrocarbons be- 

 long to two series, one called the Marsh Gas Series and 

 the other the Olefiant Gas Series, because these bodies are 

 the first members of their respective series. The table 



