Synthesis by Sunlight in Relationship to the Origin of Life. 173 



1000 of ammonium carbonate, and a mere trace of deci-normal caustic soda 

 throws it completely down. It is in a delicately reactive metastable condi- 

 tion, which reminds one forcibly, as it did Graham 50 years ago, of the 

 proteins and the constituents of living cells. 



When set up in the " Uviol " apparatus and the transmitted light observed 

 with a spectroscope, it is seen that the bright lines of the mercury arc 

 spectrum in the blue and violet have entirely disappeared, and the only ones 

 now visible are those of the red, orange, and green. An examination of the 

 solar spectrum shows complete absorption of all higher wave-lengths than 

 green. 



There is this difference between the solar and the mercury arc light 

 absorption, that in the former there is a continuous spectrum absorbed from 

 green onward, while in the 'mercury arc spectrum the absorption is that of 

 three sets of wave-lengths, one at the junction of green and blue, the other 

 far over in the blue, and the third in the violet portion of the visible 

 spectrum. We have not hitherto been able to observe the absorption of the 

 ultra-visible rays. The light energy from these definite wave-lengths of 

 the spectrum seems, however, from the results recorded below, to be very 

 effective for the particular synthesis under consideration. 



In describing the synthetic results with the ferric oxide colloid, a few 

 earlier experiments made in glass vessels with rather poor daylight illumina- 

 tion may be passed over, merely remarking that these led us on to the 

 others in which unmistakable evidence of organic synthesis was obtained, 

 and only the latter are here recorded. With sufficient illumination either 

 with sunlight or the mercury arc spectrum, and especially when " Uviol " 

 glass or quartz has been used, we have never failed to obtain clear evidence 

 of synthesis. 



Experiment I. — A dilute solution of colloidal ferric hydroxide containing 

 - 2 per cent, of Fe203, was placed in a thin blown flat-sided glass bottle, 

 made like a wash-bottle with ground glass stoppers. A slow current of 

 carbon dioxide, washed by passing through a wash-bottle containing water, 

 after evolution from marble in a Kipp apparatus, was passed through the 

 colloidal solution during two days of fairly bright sunshine on the laboratory 

 roof. On distillation this gave a moderately strong positive reaction to the 

 Setoff s test. 



Experiment II. — A glass soda-water syphon with a " sparklet " apparatus 

 attached was charged with 500 c.c. of distilled water and 5 c.c. of a colloidal 

 ferric oxide solution, and after dilution contained about - 05 per cent, of 

 colloidal ferric oxide. This was saturated with carbon dioxide by a sparklet 

 bulb, and left on the roof for a period of 20 days, in which there were about 



