520 



Hence it is seen that the chemical rays reflected at different times 

 and hours not only possess quantitative but also qualitative differ- 

 ences, similar to the various coloured rays of the visible spectrum. 

 Had nature endowed us with the power of discriminating the chemi- 

 cal rays, as we do the visible ones, by impressions of varying colour, 

 we should see the rosy tints of morning pass in the course of the 

 day through all the gradations of colour until the warm evening 

 ones at length succeed. 



A long and continued series of observations must be made before 

 we are able to appreciate the influence which these qualitative differ- 

 ences in the chemical rays exert upon the photochemical pheno- 

 mena of vegetation. That this influence must be of the greatest 

 importance is evident from the varying effects produced in other 

 photochemical processes by differences in the solar light. We need 

 only mention in proof of this assertion, the fact, well known to all 

 photographers, that the amount of light, photometrically speaking, 

 gives no measure for the time in which a given photochemical 

 effect is produced, and that a less intense morning light is always 

 preferred for the preparation of pictures to a bright evening light. 



XI. " On the Causes and Phenomena of the Repulsion of Water 

 from the Feathers of Water-Fowl and the Leaves of Plants." 

 By GEORGE BUIST, D.C.L. of Bombay, F.R.S. Received 

 April 3, 1857. 



Happening to reside in Bombay, in the neighbourhood of a number 

 of small tanks or ponds abounding with the Lotus or sacred bean 

 of India, and with four different varieties of Water Lily, I was 

 struck with the different appearances presented by these when im- 

 mersed in water, or when water was sprinkled on them. The leaves 

 of the lily, like those of the Lotus, floated with considerable buoy- 

 ancy on the surface, but never, like the Lotus, rose above it, on a tall 

 independent stem. The lily leaf is full of holes about the size of a 

 pin's head, and serrated at the edges. Through these, when the 

 leaf is pressed down, the water perforates freely. The upper surface 

 of the leaf is smooth and shining, and water runs off it without wet- 

 ting it, as it does off a piece of glass or greased surface. When 



