l86 ABIOGENIC ORGANIC-CHEMICAL EVOLUTION 



cated, but in aqueous solution the process took on certain 

 new characteristics. 



We must first say a few words as to the concentration of 

 organic substances which could have been attained in the 

 waters of the primaeval Earth. In this connection it is some- 

 times maintained that the quantity of hydrocarbons and their 

 derivatives formed on the surface of the Earth must have 

 been infinitesimal in comparison with the quantity of water 

 in the primitive ocean and that, consequently, their con- 

 centration was quite negligible. For this reason any further 

 transformation of the organic substances in the hydrosphere 

 was almost precluded because, on account of their great 

 dilution, the distances between the molecules were so great 

 that they could hardly come into contact with one another. 



In this connection it may not be out of place to recall an 

 example once produced by Lord Kelvin^^ 



138 



Suppose that you could mark the molecules in a glass of water ; 

 then pour the contents of the glass into the ocean and stir the 

 latter thoroughly so as to distribute the marked molecules uni- 

 formly throughout the seven seas ; if you then took a glass of 

 water anywhere out of the ocean, you would find in it about a 

 hundred of your marked molecules. 



In the case under discussion, however, we are certainly 

 not dealing with a glass of organic substances but with 

 incomparably larger quantities. H. C. Urey has calculated 

 that, if only half the carbon now existing on the surface of 

 the Earth took the form of an aqueous solution of organic 

 substances, then the primaeval ocean would consist of a lo per 

 cent solution of such substances. (One must, of course, bear 

 in mind that the amount of water on the surface of the Earth 

 at that time was about one-tenth of what it is now.) There 

 is thus no question of such wide dispersal of organic com- 

 pounds in the waters of the primitive ocean or of such low 

 concentrations as to preclude the possibility of organic mole- 

 cules reacting with one another. On the contrary, even the 

 mean concentrations were very high, quite sufficient for the 

 later development of more and more complicated and diverse 

 carbon compounds by polymerisation and condensation. 



