The Original Formation of Amino Acids 



155 



discharge, those which are thermodynamically capable of occurring spon- 

 taneously will be favoured. Obviously, more favourable conditions for the 

 reaction will be present in a mixture in which carbon monoxide is exchanged 

 for hydrogen, and this, from geochemical considerations, would appear to have 

 been a possible component of the primaeval atmosphere of the Earth, while 

 not destroying its reducing character. From this point of view the formation of 

 amino acids was facilitated when the atmosphere was depleted of hydrogen and 

 contained a certain amount of CO. In fact, in this case the formation of alanine, 

 for example, could proceed in accordance with the overall equation: 



CH4 + 2CO + NH3 -> CH3 • CH(NH2) • COOH 

 A Zo = — 5900 cal/mole 



Fig. 3. Diagram of apparatus for the synthesis of amino acids 

 in an electric discharge. 



In fact, a certain amount of CO was formed in Miller's apparatus when electric 

 discharges were passed through mixtures of CH4 and H2O (1-10%), but the 

 alteration in the composition of the starting mixture which this entailed had a 

 somewhat damping effect on the reactions which were going on. We therefore 

 tried Miller's experiments leaving hydrogen out of the mixture altogether and 

 substituting CO. 



We carried out our experiments in an apparatus constructed in accordance 

 with Miller's diagram (Fig. 3) [6]. At first we repeated Miller's experiments 

 using a gaseous mixture of the same composition as that which Miller used and 

 we were able fully to confirm his results, obtaining identical two-dimensional 

 chromatograms. To supplement our test of the possibility of bacterial contami- 

 nation, we carried out experiments lasting 80 hours, which were the same apart 

 from the absence of electrical discharges, and obtained wholly negative results. 

 It is obvious that when water is continually boiling and the gas is circulating in 

 the electrical discharge, bacterial processes can be excluded. 



Experiments with mixtures containing CO were carried out in a spark dis- 



