310 
ON VESICATING APPLICATIONS. 
Acetum Cantharidis was made according to the formula of 
the London College, and samples of the same were obtained 
from some of the first houses in town. The specific gravity 
of these varied from 1.059 to 1.061; 100 grains required from 
70 to 72 grains of crystallized carbonate of soda for saturation. 
They were found to be of equal vesicating power; producing 
a blister in about three hours, when applied to the arm under 
a piece of adhesive plaster. 
Experiment 1. — Acetum Cantharidis was carefully evapo- 
rated at a temperature not exceeding 100° Fahr., until re- 
duced to the consistence of an extract. This had a bright 
transparent reddish brown appearance, with a slight smell of 
Cantharides, and a strong acid, not unpleasant taste. 
Experiment 2. — A small quantity of the product of Experi- 
ment 1, was neutralized by the addition of a few drops of 
solution of ammonia, then spread on a piece of adhesive plaster 
and applied to the skin of the arm for twelve hours. No sen- 
sible effect was produced. 
Experiment 3. — A small portion of the product of 
Experiment 1 was neutralized with carbonate of soda, and 
applied in the same manner as last experiment, with the same 
result. 
Experiment 4. — A portion of the product of Experiment 
1 was washed with distilled water to remove the free acid, 
and the residue applied to the skin for twelve hours, without 
any effect. 
Experiment 5. — The product of Experiment 1 was exposed 
to the atmosphere until the acetic acid was nearly all evapo- 
rated, and then applied to the skin as before for twelve hours, 
a slight redness of the skin was produced. 
Experiment 6. — Acetum Cantharidis was neutralized with 
caabonate of soda, then carefully evaporated until crystals of 
the acetate of soda were formed, and afterwards digested for 
three hours in rectified ether, with frequent agitation. The 
ether was then decanted off and allowed to evaporate sponta- 
neously. After the evaporation of the ether, a very minute 
portion of yellow liquid was left, which reddened litmus 
