ON CANTHARIS VESICATORIA. 87 
advantage is likely to arise from the separation of the can- 
tharidin, it will be attained by its incorporation in the 
form now proposed, at the same time that we shall incur 
no risk of diminution in strength by a deviation from long 
tried experience. 
Take of Cantharides in fine powder, gxij. 
Resin, Yellow Wax, Lard, of each §viij. 
Ft. Ung. S. A. 
Take of Cantharides Pulv., gvj. 
Spt. of Turpentine, giij. 
Olive Oil, gif. M. 
Simmer over a slow fire for two hours ; raise the tempera- 
ture gradually to the boiling point; filter and evaporate 
over a water-bath until all the spts. turpentine is driven off; 
then thoroughly incorporate this solution with the cerate, 
immediately after the flies have been added, stirring con- 
tinually until cool. The object of adding the spts. turpentine 
is for the purpose of more effectually dissolving the can- 
tharidin, and the peculiar volatility of this article affords 
ready means of getting rid of it, after it has performed this 
function. 
Several other cerates have been proposed for the officinal 
cerate ; one of which directs to make a saturated decoction 
of flies in olive oil, by heat, straining and adding a sufficient 
quantity of wax to render it of a proper consistence ; and 
another is, to make an etherial extract of cantharides, and 
add twice the same quantity of wax: but neither of these 
will be likely to supersede the above cerate. 
Various complaints have been made by physicians and 
their patients of the inefficacy of blisters, which are very 
embarrassing to the apothecary, especially when he is con- 
fident that the cerate has been prepared with great care, 
and that the cantharides used were of the first quality. 
Having devoted much attention to the matter, I have found 
that the principal reason of failures consists, in a great mea- 
