l82 ABIOGENIC O RG AN IC- C HE MI C AL EVOLUTION 



It is, however, not dear from the paper to what extent the 

 authors were able to verify their sclieme by direct experi- 

 ment. 



We sliall find a sounder experimental basis for our 

 opinions as to the changes which organic compounds must 

 have undergone in the primaeval atmosphere of the Earth 

 under the influence of ultraviolet radiations in the numerous 

 laboratory experiments using artificial sources of light. Like 

 water, ammonia and hydrocarbons are split when they absorb 

 radiations belonging to different parts of the ultraviolet spec- 

 trum. This leads to the formation of various radicals such as 



— H, — OH, =NH, — NHa^ =CH, ^^CHa, — CH3, — CN, C2H, CgHo 



and CgH^. When the gas is highly rarefied, as is the case in the 

 outer layers of the atmosphere, these radicals can exist as 

 such for a longer or shorter time. However, as the pressure 

 increases, their life span decreases quickly because they 

 combine with one another to form stable compounds. When 

 this happens, all possible combinations occur and thus there 

 arises a great diversity of substances.^^* Contemporary 

 scientific literature contains an immense amount of material 

 concerning the transformation of organic substances by ultra- 

 violet radiation. The saturated hydrocarbons only absorb 

 radiation of very short wavelength at the margin of the 

 ultraviolet spectrum but the olefines can also undergo chemi- 

 cal changes under the influence of radiations having a 

 wavelength greater than 2000 A. The action of ultraviolet 

 radiation brings about polymerisation and isomerisation of 

 these hydrocarbons. They are also oxidised, mainly at the 

 expense of the oxygen arising from the photolysis of water. 

 This oxidation leads to the formation of various alcohols, 

 aldehydes and ketones, which can be further oxidised or 

 broken down photochemically to give co, H2 and new 

 derivatives. Under the continued action of ultraviolet 

 radiation the monobasic acids thus formed give rise to co,, 

 hydrocarbons and small amounts of co and Ho. The dibasic 

 acids lose CO2 and are transformed into monobasic ones. 

 Various nitrogen-containing derivatives may also easily be 

 formed by reactions with ammonia, hydrazine and such sub- 

 stances. ^^^ In this way the great diversity of oxygen- and 

 nitrogen-containing derivatives of hydrocarbons which ap- 



