SOURCES OF ENERGY 165 



we must mention the energy of the disintegration of the 

 atoms of the naturally radioactive substances, which were, 

 for the most part, concentrated in the granitic envelope of 

 the lithosphere. The heat passing from the centre of the 

 Earth to its surface amounts to lo^^ ergs /year or 2-5 x 10^' 

 kcal/year/** This is some thousands of times less than the 

 amount of energy received by the surface of the Earth from 

 the Sun. 



G. Boitkevich'^ estimates the total amount of radiogenic 

 heat of the crust of the Earth at 4-7 x 10'^ kcal/hour or 

 4-1 X 10^* kcal/year. Even if we assume that the radioactivity 

 of the Earth was several times greater in the remote past 

 than it is now (on account of the breakdown of *°k and -^^u), 

 amounting to 2 x 10" kcal/year, the radioactivity of the 

 crust of the Earth must have played a considerably smaller 

 part in the chemical transformation of carbon compounds 

 than the energy of light, the more so as the greater part 

 of the radioactive energy was dissipated as heat. Neverthe- 

 less, we certainly cannot discount it/® 



As early as 1913 J. Stoklasa and colleagues" drew attention 

 to the possibility that the primary synthesis of sugars from 

 cOo could occur under the influence of radium emanation. 

 We meet with the same idea in the works of many later 

 authors such as Becquerel, who invoked the radioactivity of 

 primaeval rocks (purely speculatively, it is true) as well as 

 ultraviolet radiations as the source of energy for the reduc- 

 tion of carbon dioxide. The possibility that a reduction of 

 this sort might have occurred is, to some extent, confirmed 

 by laboratory investigations. For example, S. C. Lind and 

 D. C. BardwelP^ obtained resinous organic substances by 

 allowing a-particles to act on mixtures of carbon dioxide or 

 carbon monoxide with hydrogen or methane. V. Sokolov^^ 

 communicated some very interesting facts to the seventeenth 

 session of the International Geological Congress in Mosco^v 

 in 1937. On the basis of his own experiments he showed 

 that the water contained in sedimentary formations could 

 be decomposed to hydrogen and oxygen under the influence 

 of the a-rays of radioactive elements. If the oxygen is removed 

 in oxidising incompletely oxidised substances, in particular 

 metals and organic compounds, then the hydrogen can reduce 



