82 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Date of Collection of Samples. Percentage of Nitrogen found. 



August 25, 1896 (1) 1.48 



(2) 1.50 



August 26, 1896 (1) 1.52 



(2) 1.52 



August 28, 1896 (1) 1.56 



(2) 1.54 



August 28, 1896 (1) 1.52 



(2) 1.52 



February 28, 1898 (1) 1.93 



(2) 1.99 



March 9, 1898 (1) 1.30 



(2) 1.31 



Careful tests for oxygen were made in the case of the gas from the 

 mains, as there was a possibility of access of air to the gas. The method 

 of testing consisted in causing the gas to bubble through a solution of 

 manganous sulphate, to which a little sodium hydroxide had been added. 

 A change in color of the manganous hydroxide which was precipitated 

 would have indicated oxygen. Tests made in this way were continued 

 frequently for an entire day while the nitrogen determinations were in 

 progress, but no oxygen was found, and iience no air could have gained 

 access to the gas. 



There seems to be reason for the assertion that fluctuations occur in 

 the composition of natural gas, but until the study of the subject is 

 carried further, and more complete data obtained, no attempt can be 

 made to connect such fluctuations with any known facts as to the geology 

 of gas. 



There is some little evidence for supposing that gas from the deeper 

 horizons is richer in nitro<j:en, and that the older productive wells yield 

 gas containing a little less nitrogen, but such may i^rove not to be the 

 case when more data are at hand. 



It seemed to be of interest to subject the incombustible gas residue, 

 obtained in the preceding work, to further study. Portions of this 

 residue were mixed with oxygen and subjected to the action of electric 

 sparks. The experiments are still in hand, and their results will be \jve- 

 sented in a later paper. It may be mentioned here that the gas subjected 

 to this treatment yields oxides of nitrogen, and in presence of caustic 

 alkali undergoes a considerable shrinkage in volume. 



If natural gas occurs in liquefied form in the rocks owing to the 



