14 



THE GASES IN ROCKS. 



THE ANALYSES. 



The analyses are numbered in table 8 in the order in which they were 

 made, and therefore furnish a chronological account of these investiga- 

 tions. At the commencement of these studies, it being deemed advisable 

 to make a rapid survey of the field and establish the range of the phenome- 

 non, in order to direct later experiments more intelligently, less attention 

 was given to securing the most trustworthy method of extracting the gas. 

 Twenty-two analyses were made during the preliminary trial stage, before the 

 apparatus was overhauled and sealed glass connections substituted for rubber 

 tubing. As it was difficult to prevent a slight leakage of air into the tubes of 

 the original apparatus, the first 22 analyses are characterized by a higher 

 percentage of nitrogen than those made afterwards under more favorable 

 conditions. Hydrogen sulphide was not determined in the first 17 analyses. 



Table 8 gives the percentage of each gas in the total volume of gas; and 

 the volume of each gas (at and 760 mm. pressure) per unit-volume of rock. 



TABLE 8. 



1 Carbonated. 



