SENSITIZED REDUCTION OE CARBON DIOXIDE S7 



dioxide consumption; and only an unsuccessful attempt to prove the 

 formation of organic matter by combustion. 



The obvious incompleteness of experimental evidence did not prevent Baly from 

 giving a detailed picture of how six-membered inositol rings grow on the surface of 

 nickel oxide around "hubs" provided by thorium oxide molecules; and how a similar 

 growth occurs in nature on the surface of chlorophyll crystals, also provided with an 

 appropriate number of "anchor points" consisting of "impurities." Baly postulated — 

 without any proof — that nickelous oxide is oxidized in light by carbon dioxide to nickeUc 

 oxide, and the latter decomposes into nickelous oxide and oxygen, and that, in nature, 

 chlorophyll a is oxidized by carbon dioxide to chlorophyll b, and reduced back to chloro- 

 phyll a by carotene (c/. page 554). 



Practically all attempts to repeat Baly's experiments elsewhere have 

 given negative results. 



Only Yainik and Trehuna (1931) have obtained positive formaldehyde tests with 

 nickel and cobalt carbonate sensitizers (but also with other colored inorganic salts, as 

 well as with "white powders colored blue, green or red by different dyes"). 



In attempting to repeat Baly's early work, Emerson (1929) found that a suspension 

 of nickel carbonate absorbs carbon dioxide (probably by bicarbonate formation) in a 

 completely reversible manner; this absorption is unaffected by Ught, and not accom- 

 panied by oxygen evolution. The negative outcome of Bell's (1931) attempts to repeat 

 the experiments with electrolytically deposited carbonates and with kieselguhr-supported 

 ferric oxide was mentioned before. Zscheile (1932) and Qureshi and Mohammad 

 (1932, 1933) repeated Baly's experiments with precipitated basic nickel and cobalt 

 carbonates, "activated" (according to Baly's preception) by illumination with a mercury 

 arc. The same tests for sugars and aldehydes as used by Baly failed to reveal the 

 presence of any carbohydrates. 



No attempts to repeat Baly's latest experiments (1939) have as yet been pubhshed. 

 We have no specific reasons to deny that the 5-7 mg. of cuprous oxide, which were 

 precipitated by FehUng's solution in these experiments, were due to the presence of 

 a reducing sugar; or that this sugar was formed by the action of diastase on "a kind 

 of starch" (although the specificity of enzymes and the optical activity of the natural 

 carbohydrates raises a difficult problem); or that this "starch" was formed by the 

 reduction of carbonic acid by fight and nickelous oxide. However, the inadequacy of 

 experimental evidence and the results of previous controls outside Baly's laboratory 

 do not encourage us to give credence to these interpretations. It may be worth stressing 

 the fact that, even if the sugar formation should be confirmed, the assertion that it 

 represents the result of true photosynthesis would remain arbitrary as long as no oxygen 

 evolution has been demonstrated. The rapid cessation of the reaction certainly does 

 not speak in favor of true catalysis. 



Baly thought that he has achieved not only the photosynthesis of carbohydrates 

 from carbon dioxide and water but also the photosynthesis of organic nitrogen com- 

 pounds. Baudisch (1911, 1916), Baudisch and Mayer (1913) and Baudisch and KUnger 

 (1916) have found that nitrate and nitrite solutions in aqueous formaldehyde or methanol 

 are converted in day fight, first into formhydroxamic acid, (OH)CH=NOH, and then 

 into a large variety of complex nitrogen compounds. Baudisch suggested that, while 

 carbon dioxide is photochemically reduced in the plants to formaldehyde (H2C=0), 

 nitrate could be reduced to a similar compound — free nitrosyl, HN=0, after which the 

 two products may imite and give formhydroxamic acid. Baly, Heilbron and Hudson 

 (1922) and Baly, Heilbron and Stern (1923) extended these experiments; and Baly, 



