54 CARNEGIE INSTITUTION OF WASHINGTON. 



Iron may act as a catalyst in this transition. A reconnaisance was made of 

 methods proposed for the reduction of carbonic acid by means of hydrogen 

 peroxide and by means of ferrous iron, hydrogen, or ferrous hydroxide 

 peroxide, which might conceivably act as a result of peroxide decomposition. 

 Repetition of the work of several observers failed to confirm the occurrence of 

 reduction in any significant quantity. However, considerable reduction does 

 occur at high pressures and work is being continued upon the possibility of 

 realizing these high pressures in ordinary systems by means of adsorbing 

 surfaces or of micro-bubbles. No positive results have been thus far obtained. 



Illuminated solutions of a pigment such as chlorophyll become increasingly 

 metastable, resulting in either coagulation or decomposition. In the presence 

 of an oxidizing agent the reducing tension of the pigment should increase, and 

 vice versa. In the event that the colloidal particles have adsorbed ions from 

 solution, the tension may conceivably be communicated to and released 

 through them as in equation (a). Potentiometric measurements demon- 

 strated that the instability tension of different illuminated dye solutions 

 was readily communicated to an electrode of platinized platinum which had 

 been previously polarized. Further experiments with solutions of methylene 

 blue and sugar demonstrated the marked acceleration of the sugar oxidation 

 when the dye is illuminated, as compared with the dark reaction. While 

 the methylene blue is itself reduced, it is regenerated upon the admission of air 

 and may be regarded as a photocatalyst for the oxidation of sugar by air. 

 Experiments in photo-reduction are awaiting an adequate method of dis- 

 posing of the hydrogen peroxide that may be formed and which reverses 

 the action into photo-oxidation. 



Effect of Ultra-violet Light on Carhamino Acids, by H. A. Spoehr and 



Arthur Locke. 



The photochemical reduction of carbonic acid and its salts to formaldehyde 

 has thus far in this laboratory been attended only with negative results. 

 The theory of Siegfried that carbonic acid is not reduced as such in the plant 

 but that CO2 combines first with amino acids and that these carbamino 

 acids enter the chlorophyll-reduction complex has gained the support of a 

 number of workers in this field. It seemed, therefore, advisable to deter- 

 mine whether solutions of carbamino acids are capable of undergoing photo- 

 reduction. Accordingly, the calcium salts of the carbamino acids of glycocoll 

 and alanine were prepared and were subjected to the light of a quartz mercury- 

 vapor lamp under a variety of conditions. It has been reported that illumin- 

 ation of solutions of amino acids in the presence of air results in the formation 

 of oxidation products which might confuse the identification of a reduction 

 product. However, during the periods of illumination used, no trace of 

 formaldehyde, ammonia, or hydrogen peroxide could be obtained from 

 glycocoll or alanine. The addition of CaCOs or FeS04 to the illuminated 

 solution was without influence. 



The illumination of ice-cold solutions of the calcium salts of glycocoll and 

 alanine carbaminate resulted in the formation of slight traces of ammonia 

 and of formaldehyde, as well as small quantities of methyl alcohol. The 

 results appear to indicate that the conversion of amino acids into calcium 

 carbaminates renders them more sensitive to photo-oxidation, but does 

 not facilitate the reduction of the bound carbonic acid to formaldehyde or 

 its equivalent. 



