2 86 



GENERAL SCIENCE 



of aerial navigation under stress of a world war, and its as- 

 sured usefulness in times of peace, is occasion for even greater 

 wonder. 



Petroleum as obtained from deeply drilled wells is a heavy 

 liquid of a characteristic disagreeable odor, and often times 

 is greenish in color. The rise of the petroleum industry in 

 the United States dates from wells driven in 1859 near 



Million Barrels 



zio 

 zoo 



190 

 IOQ 



no 



/BO 

 ISO 



140 

 I3O 



HO 



no 

 too 



90 

 00 

 70 

 60 

 50 

 40 

 JO 

 ZO 

 10 



FIG. 91. Production of petroleum in the United States from 1860 to 1910. 



Titusville, Pa. The accompanying graph shows the rapid 

 increase in its production in this country. For years kero- 

 sene was one of the most important products of the refining 

 of petroleum. Its use in lamps for household illumination 

 became world-wide. Knowledge of the importance of 

 numerous other products from the refining of petroleum, 

 and of the manner of their separation from one another, may 

 be gained in the study of Chemistry. Among these products 



