144 
CHANGES PRODUCED BY THE SOLAR RAYS. 
The behaviour of the higher sulphurets of ammonium 
towards prussic acid furnishes an admirable test for this 
acid. A couple of drops of a prussic acid, which has been 
diluted with so much water that it no longer gives any cer- 
tain reaction with salts of iron by the formation of prussian 
blue, when mixed with a drop of sulphuret of ammonium 
and heated upon a watch-glass until the mixture is become 
colourless, yields a liquid containing sulphocyanide of am- 
monium, which produces with persalts of iron a very deep 
blood-red colour, and with persalts of copper, in the pre- 
sence of sulphurous acid, a perceptible white precipitate of 
the sulphocyanide of copper. — Chem. Gaz. from Liebig's 
Jinnalen. 
ART. XLVIII. — ON THE CHANGES PRODUCED ON SOME 
DRUGS AND PHARMACEUTICAL PREPARATIONS BY THE 
SOLAR RAYS. 
By Mr. Robert Hunt. 
It has long been noticed that a peculiar change is fre- 
quently produced by the continued exposure of medicinal 
preparations to the influence of daylight, a change not 
merely in the colour of the article, but in its medicinal pro- 
perties. To adduce a few instances, ginger (pulv. zingi- 
beris Jam.) loses its fine yellow colour, and becomes white, 
with loss of its pungency. The powders of the leaves of 
hemlock (conium,) foxglove (digitalis purpur.) henbane 
(hyoscyamus,) &c, becomes a dirty yellow, and when this 
change has taken place, it is well known that no depen- 
dence can be placed upon these active drugs producing 
their peculiar influences on the system. The powders of 
