ON HYDRARGYRUM CUM CRETA. 113 
Take of Citric acid, six ounces. 
Carbonate of magnesia, four ounces. 
Lemon syrup, twelve fluid ounces. 
Water, a sufficient quantity. 
Dissolve the citric acid in two pints of the water, previously 
heated ; add to it three ounces and a half of the carbonate, 
and as soon as it is dissolved, strain or filter the solution as 
the case may demand ; distribute it equally between the 
six bottles, and add to each two fluid ounces of lemon 
syrup. The remaining half ounce of carbonate is then tri- 
turated smoothly with sufficient water to make six fluid 
ounces, and a fluid ounce of the mixture added to each 
bottle, which should then be filled with water, immediately 
corked, and tied over securely. In the course of half an 
hour, with occasional agitation, the carbonate will be dis- 
solved, and the eliminated carbonic acid retained by the 
solution, if the corks prove good. 
ART. XXX.— ON HYDRARGYRUM CUM CRETA CHANGED 
BY OXIDATION. 
By William Procter, Jr. 
Within a few years past a number of instances have been 
noticed in this city, and I believe in Baltimore also, where 
the administration of this mercurial preparation has pro- 
duced unlooked for effects, not at all attributable to its ac- 
knowledged constituents. My attention was called to this 
fact more especially by observing a change in the appear- 
ance of a specimen of the preparation in my possession, and 
which I had carefully prepared by the formula of Dr. David 
Stewart of Baltimore, as modified by the late Peter Leh- 
man, (Amer. Journ. Pharm. vol. 16, page 9,) from pure 
materials. In this specimen which is about 18 months old, 
the lower undisturbed portion of the powder, immediately 
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