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XXVI. Some observations on Corrosive Sublimate. By John 
Davy, M. D. F. R. S. 
Read June 6 , 1822. 
X am not aware that the operation of light on corrosive sub- 
limate, has yet been minutely considered. It is known that 
the liquor hydrargyri oxymuriatis of the London Pharmacopoeia 
is decomposed by light ; it has been stated, that the compound 
itself, when exposed to light, undergoes the same change ; 
and it has been recommended, in consequence, to keep it in 
black bottles. 
With a view to acquire some precise information on this 
subject, the following experiments were instituted. 
A few grains of corrosive sublimate, in the state of fine 
powder, were exposed to sunshine for 14 days in a small 
glass tube, corked and sealed. No change was then pro- 
duced, as was proved by the corrosive sublimate dissolving 
entirely in muriatic acid. 
A solution of corrosive sublimate in distilled water was 
exposed to sunshine for the same length of time. A thin 
white crust formed, which was found to be calomel ; and 
traces of free muriatic acid were detected in the solution. 
Some liquor hydrargyri oxymuriatis and solutions of corrosive 
sublimate in rectified spirit and in ether were exposed to sun- 
shine for the same time. In the former, a considerable crust 
