20 



THE GASES IN ROCKS. 



TABLE 8 Continued. 



1 In order to see whether the methane came from hydrocarbons soluble in alcohol or ether, this material, after 

 being very finely pulverized, was digested with alcohol (free from organic impurities) for 20 hours ; then with fat- 

 free ether for 45 hours. It was then thoroughly washed with ether on a filter which had previously been treated 

 with the same fat-free ether. Afterwards dried at 100 in an oven. 



2 To get rid of all carbonates the powder was treated with concentrated nitric acid for 66 hours. Much gas was 

 given off, including a copious evolution of nitric oxide. The powder was washed until all traces of acid were re- 

 moved, after which it was dried in an air-bath at 115. This material heated then gave No. 87. 



3 Treated with dilute sulphuric acid for three days in a vacuum. The powder was washed on a filter until the 

 filtrate was no longer made turbid by barium chloride, and then dried in an oven and heated in an air-bath at 125 

 for over an hour. 



4 Nos. 92 and 92a. A perfect vacuum was maintained between these two combustions. 

 6 Sulphate. 



6 Carbonated. 



7 The high percentage of nitrogen shown in this analysis is not due to leakage of air, for the pump held its vac- 

 uum for days afterwards during the spectroscopic examinations. The yellow helium line, D$ (\= 5876) stood forth 

 brilliantly, "but no argon lines could be seen in the spectrum. 



