SOURCES OF SEGREGATED CARBON. 967 



carbon in the original rocks and from the atmosphere and hydrosphere. 

 Furthermore, the segregation of carbon from widely dispersed material is 

 essential to life, and life has profoundly modified many geological processes. 

 The segregation of carbon by the various geological processes in limestone, 

 in organisms, and in coal explains the great importance of this sparse 

 element in the genesis of the earth. 



SOURCES OF SEGREGATED CARBON. 



It has been seen that fixed carbon exists in the salts of the ocean and in 

 the lithosphere as a carbonate and as hydrocarbons. The important pro- 

 cesses now producing these various carbon compounds are those involved 

 in the interaction of the carbon dioxide of the atmosphere, of organic bodies, 

 and of the rocks. If we apply the fundamental hypothesis of geology that 

 the processes now at work explain past results, we must assume that the 

 carbon dioxide for carbonation and that for the carbonaceous deposits is 

 derived indirectly from the atmosphere. It has been seen that the amount 

 of carbon required for this work is many thousands of times the amount 

 of carbon dioxide now free in the atmosphere, and many hundred times 

 the amount free or potentially free in the hydrosphere. The amount of 

 carbon dioxide in the atmosphere may have been originally vastly greater 

 than at present, but even if this were so the demands upon carbon have 

 been so great that it is probable that the atmosphere has been replenished 

 in that compound. There are several possible sources of carbon dioxide 

 for the replenishment of the atmosphere. 



An important immediate source of carbon dioxide is the ocean. The 

 amount of carbon dioxide in the hydrosphere, computed on the basis of a 

 content of 0.002 per cent of carbon (Clarke's estimate), is 96,531,915,000,000 

 metric tons. Dittmar's estimate of the entire carbon dioxide of the ocean 

 is 70,350,160,000,000 metric tons, or considerably less than Clarke's. Of 

 Dittmar's total he estimates the loose carbon dioxide (i. e., the excess of 

 carbon dioxide of bicarbonates above that required for normal carbonates 

 and the free carbon dioxide together) of the ocean to lie between 35,200,- 

 000,000,000 and 52,800,000,000,000 metric tons. Supposing the true 

 amount to be the average of these, this would give 44,000,000,000,000 

 metric tons or 19.3 times the amount of carbon dioxide in the atmosphere 

 as calculated by Dittmar." According to Schloesing- the carbon dioxide 



«Dittmar, William, Report of voyage of H. M. S. Challenger, 1873-76; Narrative of the cruise, 

 vol. 1, pt. 2, 1885, pp. 954-955. 



