THE ANALYSES. 

 TABLE 9. Analyses classified by groups of rocks. Concluded. 



25 



i The two bituminous shales which derived the bulk of their gas from the distillation and decomposi- 

 tion of organic matter are necessarily omitted from the average. 



TABLE 10. Various minerals. 



It should, perhaps; be stated that in making this and other averages 

 of analyses, in those cases where, on account of excessive carbonation, no 

 figures are given for carbon dioxide, the average amount of this gas cal- 

 culated from the other analyses is assumed to be present in those rocks 

 marked "carbonated." This addition is added to the average total and 

 makes this figure slightly greater than the average of the column which it 

 foots. The same method has been used for carbon monoxide in the three of 

 Travers's analyses where carbon monoxide and hydrogen are put together. 



