ABSTRACTION OF OXYGEN FROM THE ATMOSPHERE. 953 



Metallic iron is known as a rare constituent of certain very basic 

 igneous rocks. When such material reaches the zone of katamorphism the 

 iron is oxidized to ferrous oxide or ferric oxide, and thus oxygen is con- 

 sumed. At the present time the consumption of oxygen by metallic iron 

 is so small as to be insignificant, but it is possible that earlier in the history 

 of the earth, before the segregation of the oxidized products at the surface, 

 not only iron, but possibly other metals, may have been oxidized in grea^ 

 quantity, and thus enormous quantities of oxygen abstracted from the 

 atmosphere. The quantity of oxygen which has thus been consumed must, 

 so far as one can see, ever be a matter of conjecture. 



The source of the water of the hydrosphere is uncertain. It may be 

 supposed that early in the history of the earth a large part of the elements 

 composing water was in a free state, although doubtless a part was also 

 combined. If any considerable proportion of the water of the hydrosphere 

 was produced by the oxidation of hydrogen during the time the sedimentary 

 rocks were deposited, the amount of oxygen thus consumed would have 

 been enormously greater than that required for the processes which have 

 heretofore been considered, indeed, many times greater than the amount of 

 oxygen now in the atmosphere. However, it is useless to speculate as to 

 the extent to which the oxidation of hydrogen took place in early geological 

 time. It is probable that during the deposition of the sedimentary rocks, and 

 even at the present time, hydrogen is being oxidized on a small scale. It is 

 seen (pp. 945-946) that hydrogen and carbureted hydrogen are constituents 

 of meteorites, and further that hydrogen occurs occluded in various rocks. 

 Hydrogen is met also in connection with fumarolic and solfataric action. 

 As already explained (p. 492), this hydrogen is supposed to be produced 

 by the reaction of the ferrous oxide upon water, according to the equation 



H 2 0+2FeO=2H+Fe 2 3 . 



So far as water is produced by the oxidation of hydrogen free or com- 

 bined oxygen is abstracted from the atmosphere. This abstraction certainly 

 occurs to some extent in volcanic districts. Phipson also holds that hydro- 

 gen, so far as it is present in the atmosphere, may be oxidized by the nascent 

 oxygen freed by plants. He grew certain plants in an atmosphere of 

 hydrogen and was thus able, as he claims, to completely oxidize all of it.° 



"Phipson, T. L., Vegetation in hydrogen: Chemical News, vol. 67, 1893, p. 303. 



