194 INTRODUCTION TO GENERAL SCIENCE 



j. 1708:90-92. Coal. 



k. 1709:228-230. Coal. 



I. 1711:272-273. Coal. 



m. 1712 : 256-259. Coal. 



138. PETROLEUM AND NATURAL GAS 



, The source of petroleum and natural gas is organic matter, 

 both animal and vegetable, which has accumulated in vast 

 masses. This material subsided like the coal-producing 

 material, and was subjected to tremendous pressure, together 

 with very high temperature. By chemical change, and a 

 process of natural distillation, this matter was changed to oil 

 and gas, both of which have collected in large pockets. On 

 account of the stratification of the rocks, an oil well must be 

 drilled through certain layers until a pocket is reached. 

 Then, if there is pressure upon the oil, due to its own weight 

 or to gaseous pressure, the oil will gush or flow out ; other- 

 wise, pumps must be used to obtain it. 



References : 



1. 1205:330-331. Petroleum and Natural Gas. 



2. 1601 : 20. Origin of Mineral Oil and Natural Gas. 



3. 1702: 109-113. Petroleum and Mineral Oils. 



4. 1703:411-412. Petroleum and Refining. 



5. 1710 : 51-53. Distillates from Petroleum. 



a. 1201 : 97-102. The Story of Petroleum. 



b. 1203 : 230-231. Petroleum and Natural Gas. 



c. 1204 : 219-222. Petroleum and its Products. 



d. 1206:166-183. Liquid and Gaseous Sunlight. 



e. 1208:82-84. The Relation between Coals and Bitu- 



mens. 



/. 1210 : 313-315. Petroleum and its Origin. 

 g. 1306 : 425-426. Natural Gas and Petroleum. 

 h. 1308 : 307-309. Petroleum and Natural Gas. 

 i. 1706 : 207-209. Petroleum. 



