RESEARCH FOR ARSENIC AND ANTIMONY. 
411 
the humours of the eye appears important, especially when 
we consider that in the better kinds of artificial illumination 
(as in the carcel lamp) the calorific intensity of these obscure 
radiations is tenfold that of the luminous radiations. 
3d. These obscure rays are intercepted in general with 
extreme rapidity by the foremost divisions of the eye; for the 
source cited, the cornea absorbs two thirds, and the aqueous 
humour two thirds of the remainder, so that a fraction ex¬ 
tremely small is presented to the other media. 
4th. As to the cause of this property possessed by the 
humours of the eye, it resides almost entirely in their aqueous 
nature ; their diathermancy is identical with that of water. 
oth. In conclusion, one more reflection seems natural in 
regard to our artificial sources of light: ought we not to con¬ 
sider them still imperfect while in the best of them there 
exists so great a disproportion between the really useful rays 
and those which are foreign to the phenomenon of vision— 
a disproportion which again becomes apparent on comparing 
the actual cost with that which should be theoretically neces- 
sarv ?—Chemical News. 
•/ 
TACTS AND FALLACIES CONNECTED WITH THE RESEARCH 
TOR ARSENIC AND ANTIMONY; WITH SUGGESTIONS FOR 
A METHOD OF SEPARATING THESE POISONS FROM 
ORGANIC MATTER. 
By Alfred S. Taylor, M.D., F.R.S. 
[Continuedfrom p, 296.) 
That this view of the facts is based on pure prejudice is 
undeniable, and a single chemical illustration will prove it. 
Standard gold contains more than eight per cent, of copper. 
Strong nitric acid may be boiled in a golden capsule made of 
this alloy without removing a particle of copper. If, now, 
any organic liquid containing a soluble salt of copper be 
placed in the capsule, and a slip of zinc be brought into con¬ 
tact with the gold through the acid liquid, the copper is 
removed from the solution, and is deposited on the gold. 
The capsule may be washed with water, and the film of 
metallic copper subsequently be dissolved in nitric acid and 
tested in the usual manner. No chemist would object to use 
the gold in such a case, merely because it contained copper; 
he would be governed by the fact, that under the circum- 
