| ON THE CHEMICAL ACTION OF THE SOLAR RADIATIONS. 265 
derably on the yellow. The chemical action commences at18 from Fig: 10. 
the line a'; the orange occupies the space of *10, the yellow about 
“16, but blending with the green; this is not easy of exact deter- 
mination; the green occupying about °25, and the blue and vio- 
let *38. There is a considerable loss of light in the spectrum. 
(22) 120. GREEN GLASS acting powerfully on all the reds of 
flowers, &c.—Cuts off one-half the red, extends the yellow, and con- 
sequently reduces the green of the spectrum. The blue is shortened 
by an extension of the violet. Although the reds of the least re- 
frangible end of the spectrum suffer considerably, those which are 
most refrangible pass this glass (copper) freely. 
(23) 121. GREEN GLass (Copper ).—Reduces the reds of spectrum ; brings 
the violet down on the blue; but the violet less red than ordinary. 
(24) 122. GREEN GLAss.—Nearly the same as the last (121). Fig. 11. 
There is little change on the lower rays, but the blue and violet 
rays are reduced to one-half their ordinary linear dimensions. 
(25) 116. DEEP 1RON-GREEN, fig. 11.—All the reds of flowers 
observed through this glass become nearly black. The spectrum 
exhibits two spots of pure crimson; perfect blackness between them. 
A spot of yellow of great purity, from which the green shades off 
into a light blue, which becomes very bright, and then passes into 
a line of indigo. The violet is entirely wanting. 
(26) 115. A PALE SMOKY-GREEN.—Acts but*very slightly upon 
any of the rays. 
(27) 44. DEEP IRON-GREEN, fig. 12.—Cuts off the lower red rays ; 
admits the permeation of the orange rays freely. The green very 
much blended with the yellow, so that it is only by adjusting with 
great care that a line of yellow can be seen. ‘The blue and violet 
rays suffer scarcely any change, the lengths of these rays being rela- 
tively as follows :—green ‘30, blue °25, violet ‘15. 
(28) 6. INTENSE COPPER-GREEN.—The spectrum appears as 
orange, green, blue and violet. The yellow rays are entirely want- 
ing ; a very thin line of red appears at the lower end of orange; the 
violet is considerably reduced by the loss of red. = 
In all the deep greens we find the violet rays almost entirely destroyed 
owing to the removal of the red. It is from results of this character that I 
am led to believe the violet rays to be due to a reappearance of red rays 
amongst the more refrangible ordinary rays. 
(29) 52. YELLOWISH-GREEN GLAss.—This glass has but very slight ac- 
tion on the spectrum, defining more perfectly than ordinary the limits of the 
_ violet, but producing no sensible change on any other of the chromatic rays. 
(30) 107. Licut Green.—The reds of flowers are Jost, the flowers ap- 
pearing purple. Yellows are also lost, the yellow blossom of the Elder tree, 
&e. becoming pure white. 
The violet rays are considerably cut off; the other rays are well-defined, 
but more green and less yellow than ordinary. 
(31) 119. Licut BoTTLE-GREEN.—Produces no evident change on na- 
tural colours ; its action on the spectrum is merely to define the spaces of 
the rays without producing any other change. 
(32) 110. Deep BOTTLE-GREEN.—Natural blues are blackened, and the 
__ paler reds suffer slightly. This glass cuts off all the most refrangible rays ; 
a band of violet, or blue with some red, is seen lining the edge of the green. 
_ The green rays very brilliant, and yellow passing to whiteness ; the red rays 
suffering scarcely any change. 






