168 



Action of Light Rays on Organic Compounds, and the Photo- 

 synthesis of Organic from Inorganic Compounds in Presence 

 of Inorganic Colloids. 



By Benjamin Mooee, D.Sc, F.E.S., and T. A. Webster. 



(Eeceived December 11, 1917.) 



(From the Department of Applied Physiology and Hygiene, Medical Eesearch 



Committee.) 



In a former paper by the present authors* it was shown that sunlight in 

 the presence of certain inorganic colloids, and notably of commonly occurring 

 substances, such as colloidal ferric oxide or hydrate, possesses the power of 

 acting upon water and carbonic acid, and yielding the energy necessary for 

 the production of formaldehyde, from which carbohydrates and other organic 

 constituents found in plants and animals might be built up. 



In a later paper it was shown by Mooref that such inorganic compounds of 

 iron occur associated in the chloroplasts of green plants, and especially 

 marked in the lowlier green organisms, and hence that such photo-synthetic 

 processes in which inorganic iron salts played the part of energy transformers 

 might be regarded as taking a part in normal photo-synthesis in the plant. 



The present paper records a continuation of these experiments. The source 

 of light energy instead of sunlight was often the light of a mercury vapour 

 lamp in a silica tube on account of the difficulty from weather conditions of 

 using sunlight during the greater part of the year. Such a lamp gives certain 

 lines of light in the ultra-violet range possessing a good deal of energy, and 

 this part of the spectrum is the most powerful in producing the effects 

 recorded, for it suffices to expose the solutions in glass tubes instead of silica 

 tubes, or to interpose even a thin plate of mica between the source of light 

 and the solution, in order to cut off nearly all of the effect. 



As in the previous paper the test used for the presence of formaldehyde in 

 the experiments with inorganic catalysts was that introduced by SchryverJ in 

 which a pink coloration is produced in presence of formaldehyde by phenyl- 

 hydrazine and potassium ferricyanide in acid solution. The test is so delicate 

 that it shows quite clearly one part in 2,000,000 of formaldehyde, and we 

 have found it most satisfactory with continued use. Some attempt has been 



* ' Eoy. Soc. Proc.,' B, vol. 87, p. 163 (1913). 

 t ' Eoy. Soc. Proc.,' B, vol. 87, p. 556 (1914). 



% 'Eoy. Soc. Proc.,' B, vol. 82, p. 226 (1910); Eeport No. 9, Inspector of Food's 

 Department of the Local Government Board. 



