and on the chemical action of the Solar Spectrum, 273 
coloured glass and great thicknesses of yellow fluid are deep- 
ened to a plum-brown in less than an hour 
Under three inches of the bichromate of potassa the paper, 
f became in eight hours sunshine of a full blue-brown. 
18. The fact of cress and pea plants growing green, under 
the influence of such powerful light as penetrated Professor 
Draper’s yellow media, will not appear at all surprising when 
we examine the rays which pass through such fluids. 
This I have done by forming a spectrum, interposing the 
coloured body between the prism and the sun. The follow- 
ing are the effects of a February sun at Devonport. 
Through a deep blue solution of the ammonia-sulphate of 
copper, the violet, indigo, blue, and a portion of the green rays 
pass. 
Through solutions of the muriate, acetate and.nitro-muriate 
of copper with iron, the green ray, and a considerable portion 
of the yellow; a trace of the blue also is evident. 
Through solutions of the bichromate and chromate of po- 
tassa, the chloride of gold and decoction of turmeric, the red, 
the yellow and the green rays are seen, and by talcing their 
impression on a daguerreotype plate a line of the blue is dis- 
tinctly marked. 
Through nitro-muriate of cobalt in ammonia, carmine in 
ammonia, and sulphuric acid and decoction of cochineal, the 
red and yellow rays alone appear to penetrate. 
THE SPECTRUM. 
Dispersed light, 
Rose hue, 
White with shade \ 
of green / 
Black band 
Dispersed light 
* The papers which accompany this article were exposed under the 
glasses and three-fourths of an inch of fluids for forty minutes. The order 
of interference and consequent colouring is plainly shown. 
Phil Mag. S. 3. Vol. 16. No. 103, April ISW. T 
