22S ON CANTHARIDIN AND ITS PREPARATIONS. 
1. Taffeta vel chart a vesicans s. cantharidalis. 
Taffetas (marceline,) stretched on a frame, or paper on a 
board, is to be painted over twice at proper intervals with an 
aqueus solution of isinglass ; when perfectly dry the liquor 
cantharidalis — prepared in the following manner, is to be 
spread over it : 
jl Ether, cantharidalis. 
Ether, sulphur, aa. §j. 
Terebenth coct. 
Colophon, aa. 3ji. 
Misce et solve. 
A painter's brush, moderately moistened with the solution, 
and softly pressed against the brim of the vessel, is then 
passed at short intervals, and always in the same direction, 
twice over the stretched material — in twenty-four hours 
once more — and again after twenty- four hours for the fourth 
time. In order to prevent the agglutination of the prepara- 
tion, it is coated after a few days with a fresh solution of 
isinglass that has already commenced to congeal. The 
taffeta and the paper are equal to one another in effect, 
only that the latter is cheaper by a fourth. Before apply- 
ing the plaster it should be wiped with a wet rag in order 
to remove the last applied coating of isinglass. 
2. Unguentum vesicans s. cantharidale. 
This ointment, prepared after the Prussian pharmaco- 
pceia, is, as I have before stated, indispensable in the treat- 
ment of children. After three or four applications it pro- 
duces within three or four hours abundant blisters, which 
entirely disappear in a few days. If prepared with equal 
parts of ether cantharidalis and fat, it operates after two 
or three applications within two hours equally intensely, 
but quicker and more sure. Half a scruple of ether can- 
tharidalis and the same quantity of hogs' lard are sufficient 
for a threefold application upon a surface as large as a crown 
piece. 
