This section is from the book "An Elementary Outline Of Mechanical Processes", by G. W. Danforth. Also available from Amazon: An elementary outline of mechanical processes.
Natural Gas, like mineral oil, is obtained from cavities in which it is confined in the earth. It is abundant in a few localities only, but the great desirability of gas has given rise to the artificial production of fuel gas from coal, and to a less degree from oil. Natural gas is composed of about 93% Ch4, with very little free hydrogen, CO, and nitrogen.
 
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