270 REPORT—1852. 
More than half of the bluerays are inactive, the action being 
confined to the space of the violet and the lavender rays. 5 
(56) 12. Rep (Gold) (14), fig.25.—A great number jj 
of experiments have been made with the hope of detecting 
some chemical action on the iodized collodion by the 
bright crimson rays which permeate this glass. In no 
instance have I been successful; instead of obtaining any 
indication of change, the only result has been the occa- 
sional evidence of a protecting action over the spot on 
which the oval red patch, described in the analysis of 
the spectrum, falls when diffused radiations have acted 
on the sensitive surface generally. 









Glasses (C.) Green Media. 
(57) 36. BRIGHT APPLE-GREEN (19), 
fig. 26.— Action appears singularly divided. 
Two spaces of most intense action, corre- 
sponding with the green and violet rays as 
shown at y, v, these being surrounded with 
a band of a chocolate-brown colour. By 
placing the glass in a strong solution of the 
hyposulphite of soda the outer band is 
readily dissolved off, but the ovals y, v resist 
for a long time the action of the solvent, 
dissolving indeed, only when the film of col- 
lodion separates from the glass. 
(58). The former result was obtained in 
London. On repeating the experiments at a a’ 
Falmouth, a very different result was ob- . 
tained. The action commencing at ‘60, and continuing to 1°60, an extended 
though much weaker action is prolonged to °35. The experiments having ~ 
been repeated several times in both localities under precisely the same con- 
ditions as regards prism, size of opening between knife-edges, length of 
spectrum, &c., these results indicate some peculiar atmospheric conditions. 
These, however, can only be determined by several sets of experiments at 
different times. 
(59) 6. INTENSE COPPER-GREEN (28), fig. 27. 
—Intense action, producing a bronzed line, 
commences at ‘60 and extends to 1°10, or over 
a space equal to°50. A weak action extends 
down to ‘45, marking the space occupied by 
the green ray. A similar modified action 
extends upward to 1°60. By long exposure a 
light fringe appears over the space occupied 
by the yellow rays, the actual chemical spec- 
trum being 1°35 in length. The fringe around ; 
the lower part of the spectrum, which is not 
readily explained, is a tolerably constant re- = 
sult. It may possibly arise from some refrac- 
tion of the rays near the Fraunhofer line B, 
within the glass plate. 
(60) 34. Green (Copper) (21), fig. 28.— 
Action commences at ‘60, and it is continued 

