46 



THE GASES IN ROCKS. 



matic waters of the intrusion, kindly furnished by Dr. C. K. Leith, were 

 used to illustrate this point. 1 Though containing very different quantities 

 of ferrous compounds, they yielded identical volumes of methane, hydrogen, 

 and nitrogen. These analyses are given in table 34. 



TABLE 34. 



The great excess of carbon dioxide in the andesite is assigned to car- 

 bonation of that lava subsequent to its formation a process to which the 

 quartz would not be susceptible. 



The observation that comparatively pure quartz yielded half a volume 

 of hydrogen suggested a quantitative analysis to determine the amount 

 of iron actually contained in hydrogen-producing quartz. For the purpose 

 quartz from Orange, New South Wales, was selected. 102.72 grams of the 

 quartz yielded 4.81 cubic centimeters of hydrogen at and 760 millimeters. 2 

 After the gas had been extracted, two different portions of the exhausted 

 mineral were digested with aqua regia one of them boiled for an hour, 

 the other being allowed to stand during several days, and occasionally 

 warmed to the boiling-point. The acid may be considered to have dis- 

 solved all the iron from which gas could have escaped. To make the case 

 certain, all of the iron detected has been supposed to have existed in the 

 quartz as ferrous oxide, although some of it undoubtedly occurred in the 

 form of ferric compounds. The iron was weighed as Fe 2 O 3 . 



First determination: 



22.22 gms. quartz contained 0.0015 gm. Fe 2 O 3 



102.72 gms. quartz would contain 00693 gm. Fe 2 O 3 



102.72 gms. quartz would contain 00485 gm. Fe 



Fe (as FeO) required to give 1 c.c. hydrogen 00748 gm. 



Maximum amount hydrogen from reaction 65 c.c. 



Hydrogen actually obtained (at and 760 mm.) 4.81 c.c. 



Hydrogen not from this reaction 4.16 c.c. 



Second determination: 



52.02 gms. quartz contained 0.0042 gm. Fe 2 O 3 



102.72 gms. quartz would contain 00829 gm. Fe 2 O z 



102.72 gms. quartz would contain 00580 gm. Fe 



Fe (as FeO) required to give 1 c.c. hydrogen 00748 gm. 



Maximum amount hydrogen from reaction 77 c.c. 



Amount of hydrogen actually obtained 4.81 c.c. 



Hydrogen not from this reaction 4.04 c.c. 



1 Analyses Nos. 70 and 71. 

 a Analysis No. 100. 





