TO THE ORIGIN OF LIFE 45 



Experiment I. Twenty c.c. of dilute colloidal uranic hydroxide 

 solution containing approximately 0-03 per cent, of Ur 2 3 were 

 placed in a test-tube on the roof, and carbon dioxide generated in a 

 Kipp, and washed as above described, was slowly bubbled through. 

 The day was a bright sunny one (May 26, 1913), and the experiment 

 was continued all day. Half of the solution was taken out, and of 

 this the greater part was distilled off from the colloid. Tested 

 with SchifE's reagent this distillate gave a distinct pink coloration 

 within half an hour. The remaining half of the colloidal solution 

 was kept on the following day, which was also a bright sunny day, 

 on the roof with carbon dioxide bubbling slowly through it ; it was 

 then tested in the same way for aldehyde, and gave a still stronger 

 reaction. Blanks were carried out with distilled water, and the 

 SchifE's reagent and the contrast was most marked, the distillate 

 from the colloid exposed to light giving a deep pink, while the dis- 

 tilled water control remained colourless. 



Experiment II. Thirty c.c. of the same dilute colloidal uranium 

 solution were taken in a wide test-tube, saturated with carbon dioxide 

 by bubbling the gas through, and then hermetically sealed. The 

 tube was left resting on its side on the roof for two days, both of 

 which had a good deal of bright sunshine. The contents of the tube 

 showed no visible alteration or precipitation at the end of the 

 period. The tube was now opened and about two-thirds of its 

 contents were distilled off. The distillate tested with SchifE's 

 reagent gave a marked formaldehyde reaction. 



Experiment III. A soda-water syphon with a " sparklet " 

 apparatus for charging with C0 2 was taken, and in it were placed 

 500 c.c. of distilled water and 30 c.c. of the stock colloidal uranium 

 hydroxide solution, giving accordingly a concentration of 0-035 

 per cent, of Ur 2 3 . 



This was charged with carbon dioxide from a " sparklet " bulb, 

 and left on the roof for thirteen days, of which seven were bright 

 days with strong sunlight. At the end of the period a portion was 

 withdrawn and distilled. It gave strong positive reactions for 

 formaldehyde with both SchifE's reagent and Schryver's test. 



The stock solution of colloidal uranium hydroxide diluted equally 

 and distilled without previous exposure to light gave negative 

 results in both tests. 



Experiment IV.: Contrast of Action of Colloidal Uranium and 

 Crystalloidal Uranium. Two glass tubes were taken of similar 



