REDISTRIBUTION OF HYDROGEN. 981 



HYDROGEN. 



According to Clarke hydrogen composes 0.94 per cent of the outer 10 

 miles of the crust of the earth, including the lithosphere, hydrosphere, and 

 atmosphere. The larger part of the hydrogen is in the hydrosphere, of 

 which it composes 10.67 per cent. According to Clarke's estimates of 1891 

 and 1900 it constitutes, respectively, 0.21 and 0.17 per cent of the litho- 

 sphere." The hydrogen of the atmosphere is inappreciable. It thus appears 

 that 0.8 or more of the hydrogen is concentrated in the hydrosphere, 

 although the volume of the lithosphere is five times as great. Hydrogen has 

 the tenth place in the scale of abundance. Practically all of the hydrogen 

 is combined. In so far as hydrogen enters into the processes of meta- 

 morphism it is in conjunction with oxygen as water. The source of the 

 water is very largely conjectural. It may be supposed that hydrogen and 

 oxygen, united as water, at the time the earth segregated, were with 

 the other ingredients in great volume. As magma crystallized the water 

 separated. This process has continued to the present time. By it some 

 explain the ocean, and hold to its continuous growth in magnitude. It is 

 possible that a considerable amount of the hydrogen for the water was 

 originally in the free state or in the form pf carbureted hydrogen. . This 

 is suggested by the fact that hydrogen and carbureted hydrogen are both 

 occluded in meteorites. If the water of the hydrosphere was produced in 

 any large measure by the oxidation of hydrogen an enormous quantity of 

 hydrogen was thus consumed. 



Probably the most characteristic reaction of the zone of katamorphism 

 is that of hydration. This process, while taking place most rapidly in the 

 belt of weathering, occurs continuously throughout the vast volume of the 

 belt of cementation. According to Clarke h the combined water in the 

 igneous and crystalline rocks liberated at 110° C. is 0.40 per cent, and above 

 110° C. 1.52 per cent; total, 1.92 per cent. In 78 shales the water liberated 

 at 110° C. is 1.34, and above 110° is 3.68 per cent; total, 5.02 per cent. 

 In 624 sandstones at 110° it is 0.29 per cent, and above 110° is 1.40 per cent; 

 total, 1.69 per cent. In 843 limestones at 110° it is 0.26 per cent, and above 

 110° is 0.72 per cent; total, 0.98 per cent. (See p. 938.) It therefore 

 appears that the amount of water in the shales is more than double and in 



a Clarke, cit., Bull. 78, p. 39; Bull. 168, p. 15. & Clarke, cit, Bull. 168, p. 14. 



