ORIGIN AND USE OF NATURAL OAS AT MANITOU. 23 



Mauitou springs, it may be helpful to recall to mind some of 

 the explanations most frequently given for the production of 

 natural gas in large quantities beneath the surface of the 

 ground. First, then, may be mentioned the slow, natural 

 distillation of the buried or fossil organic matters that are 

 found in many strata, notably in the shales. The volatile 

 products evolved in this manner contain large quantities of 

 marsh-gas and similar combinations of carbon and hydrogen, 

 with but little carbon dioxide. The wide distribution of gas 

 wells over the country attests a very general chemical action 

 of this sort yielding combustible gases. At Colorado City, 

 three miles distant from the Manitou springs, a small flow of 

 combustible gas has been obtained from the two wells already 

 bored. A second cause, obviously a true one where the proper 

 conditions exist, is found in the heat of lavas or igneus rocks 

 where they come directly in contact with limestones. It may 

 be doubted whether much gas is ever produced by actual rise 

 of temperature in this way without the aid of moisture, but 

 unquestionably superheated waters carrying dissolved mineral 

 matters and accompanied by vapors and ^ases produced by 

 such igneus rocks, would effect the liberation of this gas. 

 Thirdly, limestones deeply buried under later deposits of 

 rock will sutfer an increase of temperature due to the rise of 

 isogeotherms, and heated mineralized waters will then bring 

 about chemical reactions with the limestones. SimjDle rise 

 of temperature alone will not suffice in such enclosed zones 

 to liberate the carbon dioxide, though with the aid of moisture 

 it may metamorphose the limestones to marble. A last cause 

 to be noticed here is the chemical decomposition of lime- 

 stones effected, with or without high heat, by acid waters or 

 by salts which react with the carbonates of lime and mag- 

 nesia, forming a new series of salts and setting free carbonic 

 acid gas. This last cause has been in part anticipated in the 

 two preceding theories of the derivation of the gas. 



As the development of a theory of the formation of car- 

 bon dioxide probably turns in no small degree upon the 

 action of substances in solution derived from the rocks, it is 

 appropriate here to consider some of the results of investiga- 



