Artificial Photosynthesis 45 



which green plants, with the help of the sunlight, 

 build up complex carbon compounds out of air, water, 

 and - salts. The cogency of these two sets of facts is 

 diminished by the fact that the ingenious chemist 

 directs operations in the one case, and the living 

 plant is the theater of operations in the other case. 



There may be a hint in the fact that cyanogen 

 (CN) and its compounds may be formed in incan- 

 descent heat, and might arise while the earth was still 

 hot. The cyanogen compounds are unstable and 

 might readily form linkages with other compounds, 

 especially when water began to be precipitated on 

 the cooling crust of the earth. 



But greater interest attaches to the recent in- 

 vestigations by Professor Baly of Liverpool and his 

 collaborateurs. There has been success in effecting 

 artificially what a green leaf effects naturally — the 

 synthesis of formaldehyde by the action of light upon 

 water and carbon dioxide. The light used was that 

 of a mercury-vapor lamp, which has very short wave- 

 lengths. As in the green leaf, the synthesis is accom- 

 panied by the liberation of oxygen. Light of a some- 

 what longer wave-length caused the molecules of 

 formaldehyde to unite to form simple sugars ; Profes- 

 sor Baly also succeeded in bringing about a union of 

 nitrites and formaldehyde in a test-tube subjected to 

 the light of a quartz-mercury lamp. Here it may be 

 remembered that a discharge of lightning through 

 the air might lead to the fixation of nitrogen, which 

 man now achieves with his powerful electric arcs. 

 Rain might bring the fixed nitrogen to the earth in 



