RESEARCHES UPOlSr THE CHEMICAIi PROPERTIES OF GASES. 235 



such considerable quantity as to render it probable that this gas is set free in the 

 process of decay. 



The same apparatus was kept in position for two and a half years after the 

 above experiments were finished. During that time a continuous production of gas 

 was observed, but it was so slow that at the end of this period only about 30 c.c. of 

 gas collected. This was found to consist of methane. 



I have examined the gases produced in swampy ground in many different places. 

 Samples were taken from streams having muddy bottoms and in which vegetable 

 matter had collected. Samples of gas have also been taken from salt marshes on 

 the coast of Maine. Gas has also been collected from the very deep accumulations 

 of mud and decaying vegetable remains found in some parts of Lake Chautauqua. 

 The general result of examinations of these gas samples may be stated to the effect 

 that the gas occurring in shallow swamps and streams consists of methane, carbon 

 dioxide and nitrogen. In some of the much deeper swamp waters, where masses of 

 vegetable debris of greater thickness are found (as in Lake Chautauqua), hydrogen 

 occurs in very small quantity. Great difficulty is experienced in taking samples of 

 gas from localities of the latter type. Tappeiner observes that the marsh-gas fer- 

 mentation is very probably a very important source of methane in nature. 



The fact that buried vegetable matters may, after a brief period of rapid gas 

 evolution, pass into a condition of extremely slow decay, adds greater force to the 

 original theory of petroleum and gas. The occurrence of so large a proportion of 

 free hydrogen among the gases evolved by vegetation in process of decay is a matter 

 of great interest, as it suggests the existence of an important source of hydrogen 

 wherever deeply submerged plant remains occur. Frankland (J. Cli. Soc, 1883, 

 p. 295) found that grass left to decay under water (air being excluded) evolved gas 

 in three days of the following composition : 



Carboa dioxide 84.63 per cent. 



Oxygen 0.13 



Hydrogen 6.90 



Other combustible gases 2.51 " 



Nitrogen 5.83 " 



Vegetable tissue, after the somewhat sudden and tumultuous evolution of gas, 

 seems to be capable of relapsing into an extremely slow and long continued process 

 of decay. After the first decomposition, such remains might become accumulated 

 and buried deeply under sediments before the tissues are materially altered. The 

 generation of gas might then proceed in the cold. It seems hardly possible to ignore 

 this probable source of natural gas in discussing any theory as to its origin, espe- 



