MEMOIR X.] THE DECOMPOSITION OF CARBONIC-ACID GAS. 



Table of the Decomposition of Carbonic Acid by Light of Di/erent 



Colors. 



should therefore expect that in a beam, passing through 

 absorbent media of such a nature that the extreme red, 

 the blue, the indigo, and violet are absorbed, this de- 

 composition should nevertheless go on. A solution of 

 bichromate of potash nearly fulfils these conditions. It 

 transmits the luminous rays in question, except a trace 

 of those which correspond to the more refrangible yel- 

 low and less refrangible green. 



A remarkable proof of the correctness of the foregoing 

 prismatic analysis comes out when leaves are made to 

 act on carbonated water in light which has passed 

 through a solution of bichromate of potash. I took a 

 wooden box of about a cubic foot in dimensions, and 

 having removed its bottom, adjusted to it a trough made 

 of pieces of plate-glass. The box being set on one side, 

 its lid served as a door, and the trough being filled with 

 a solution of bichromate of potash, the sun's beams came 

 through it, and in the interior of the box leaves and car- 

 bonated water could be exposed to the rays that had 

 escaped absorption. The thickness of the liquid stra- 

 tum was about half an inch. I had several such boxes 

 made, so that I might compare the simultaneous effect 

 of light that had undergone absorption by different me- 

 dia. They formed, as it were, little closets, in which 

 bodies could be exposed to parti-colored light blue, 

 yellow, red, etc. 



