194 C. REID 



In a second set of experiments the solutions were allowed to evaporate completely to 

 dryness under irradiation, and irradiation continued for about i hour after liquid water 

 had disappeared. This resulted in a considerable amount of polymeric material, which 

 was estimated after dialysis in cellophan for 24 hours. 



The substances investigated were methanol, formaldehyde, paraformaldehyde, ammo- 

 nium carbonate, ammonium salts, free ammonia in basic solution, hydroxylamine, nitrites 

 and nitrates. Many experiments were done both in air and in an atmosphere of CO2, with 

 CO2 bubbling through the solution and filling the whole apparatus. Since the amino acid 

 yields were always better under the latter conditions these are the ones reported. The 

 concentrations of reactants were either 10% or, as in the case of paraformaldehyde, the 

 maximum set by the solubiUty. Since the question of whether life began in concentrates 

 of inorganic salts or in very dilute solution is unresolved, we saw no reason for working 

 at very high dilutions. 



Products 



Apart from hexamethylenetetramine, which formed in large quantities at pH > 7-5 

 when formaldehyde and ammonia were present, and in smaller quantities when they 

 were produced during the photoprocess, only glycine and formic acid were isolated (from 

 the hydroxylamine-formaldehyde CO2, in presence of Fe+++ system) in quantity large 

 enough for positive identification (0-03% of CH2O was converted to glycine). All other 

 identifications are from Rp values and co-chromatography. So far we have concentrated 

 on amino acids although some spots not due to amino acids are also present. Table i 

 shows the substances so far identified. Table 2 gives the efficiency of the various sub- 

 stances, based on the intensity of the glycine spot. 



Table i. — Products 

 In alkaline soln. 



CH2 



N— GHz CH2— N 



Glycine 



Alanine 

 Histidine(?) 



N 



I 

 CH2 CH2 CH 



\ 



\ 

 \ 



N' 

 Hexamethylenetetramine 



AtpH6 



Glycine 

 Alanine 

 Formic acid 

 Glutamic acid ? 

 Leucine ? 



Table 2 

 Order of efficiency^ based on glycine formation 

 Source of N 

 H2CO + Basic Soln. NH2OH > NO2' > NH3 

 H2CO + Acidic Soln. NH2OH > NH4+ > NO2' > NO3' 



Source of C 

 HCOOH > (H2CO)„ > H2CO > CO2 > COs" 

 (For polymer formation H2CO best) 



