The Origin of Organic Molecules 9 



2,000 A, but it is larger in amount than all nonradiant sources of 

 energy. It is evident also that the appearance of relatively simple 

 carbon-oxygen-hydrogen compounds would extend the region of ab- 

 sorption into the 2,000 to 3,000 A region where much larger amounts 

 of energy are available. However, even after 4.5 billion years, living 

 organisms are using only a small fraction of all the energv of sunlight. 



Miller 9 s experiments 



Miller's synthesis of carbon compounds from simple substances is 

 too well known to require any serious review. The conditions used 

 would not be those used today for the same experiments. It was sup- 

 posed that the primitive atmosphere contained an appreciable con- 

 centration of hydrogen. The high atmosphere of the earth is at some 

 2000°K or even more, as was shown to be true by Spitzer ( 1952 ) , and 

 under these conditions elementary hydrogen would be lost very 

 rapidly. Hence today experiments omitting hydrogen as such would 

 appear more appropriate. Also it should be noted that electric dis- 

 charges were used only because they were easy to provide and not 

 because it was supposed that lightning was the primitive source of 

 energy. It was expected that the electric discharge would activate 

 molecules in a way that would be similar to that produced by ultra- 

 violet light. Table 4 gives the list of substances produced by Miller 

 in one of his experiments. For the first time weighable amounts of 

 substances present in living organisms or readily produced from their 



Table 4. Yields from sparking a mixture of CH 4 , NH 3 , H 2 0, and H?; 710 mg 

 of carbon was added as CH t 



Compound 



Yield, 

 moles (X10 5 ) 



Compound 



Yield, 

 moles (X10 5 ) 



