ON ORGANIC COMPOUNDS 81 



1. Water alone, freshly redistilled, was saturated by a stream 

 of carbon dioxide and then exposed in a quartz test-tube during the 

 whole of a bright summer day on the roof to direct sunlight; along- 

 side it in a similar quartz test-tube was exposed a 1 per cent, 

 solution of ferric chloride also saturated with carbon dioxide, and 

 a third test-tube filled with 1 per cent, ferric chloride saturated 

 with carbon dioxide was kept in a dark cupboard. 



Tested at the end, after distilling away from the iron salts, the 

 distilled water tube and ferric chloride tube kept in darkness gave 

 a negative result, while the tube of ferric chloride exposed to sunlight 

 in presence of carbon dioxide gave a bright pink colour with 

 Schryver's reagent corresponding to about 1 in 500,000 of form- 

 aldehyde. 



2. A solution of 1 per cent, ferric chloride was made up with 

 distilled water which had been freshly boiled and was free from 

 carbon dioxide; this solution contained in a quartz test-tube was 

 exposed during a whole week of bright sunshine in June on the labo- 

 ratory roof. It was then distilled and tested with negative results. 



These experiments clearly show that an inorganic energy trans- 

 former is necessary, and that carbon dioxide alone in aqueous 

 solution in sunlight does not form formaldehyde ; secondly, that the 

 formaldehyde is not a decomposition product of traces of more 

 highly organised substances, but is actually built up by the inorganic 

 colloid absorbing the energy of the sunlight and so becoming 

 activated and reacting on the water and carbon dioxide, transferring 

 the energy and producing formaldehyde. 



Both the elements hitherto described viz., uranium and iron 

 form higher and lower oxides, and it might, therefore, be urged 

 that the higher oxide became reduced by the energy of the sunlight 

 to a lower oxide with greater energy content, and that this lower 

 oxide parting with its acquired energy to the water and carbon 

 dioxide formed the formaldehyde to which the energy of the sun- 

 light was thus indirectly transferred. Such a view is of interest 

 because similar changes do actually occur in certain life processes, 

 where various types of micro-organism, such as iron organisms, 

 sulphur organisms, and nitrogen- assimilating or carbophilous 

 organisms carry out similar energy transformations. The so-called 

 iron bacteria are capable in darkness, as within an iron water- 

 cistern or water-main, of utilising the energy of metallic iron or 

 ferrous oxide, when given out in the process of oxidation to the ferric 



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