CHAPTER XX 

 PETROLEUM OR ROCK OIL 



Petroleum (from two Greek words, petros meaning rock, 

 and oleum meaning oil) is rock oil. Rock oil is one of the 

 minerals of the earth. It occurs in California in great quanti- 

 ties. The geology of oil has become a science in itself. Petro- 

 leum geologists are specialists in oil, just as mineralogists are 

 specialists in minerals; paleontologists are specialists in fossil 

 remains of living things, remains of which are entombed in the 

 rocks; soil specialists who study the soils formed from the rocks; 

 and stratigraphers who study the character of rock formataions 

 laid down in once horizontal beds on sea bottoms. To every 

 man according to his several ability. 



The Origin and Nature of Oil 



Rock oil is derived in some way from the rocks. Where it 

 comes from, that is, how it was formed in the earth, is not 

 certainly known. It is one of the minerals of the earth. It has 

 been thought by some that it has been formed by some chem- 

 ical process in the rock formations of the earth. It is composed 

 of carbon and hydrogen. The greater part of all plants is some 

 combination of these same chemical elements, with oxygen. 

 Sugar, starch and wood are carbon, hydrogen and oxygen. 

 The tissues of animals are also carbon, hydrogen and oxygen,' 

 with nitrogen. 



Natural gas, petroleum, bitumen, and asphaltum are all 

 essentially compounds of carbon and hydrogen, or mixtures of 

 such compounds. They are known as hydrocarbons. Consist- 

 ing essentially of carbon and hydrogen, they contain also many 

 impurities, as sulphur compounds, nitrogenous substances, and 

 other impurities. The simplest hydrocarbon is marsh gas, hav- 

 ing the chemical symbol CH 4 . All the hydrocarbons fall into a 



