ON CEKATUM CANTHARIDIS. 
To the Editor of the American Journal of Pharmacy. 
Dear Sir, — Having for some time been in the habit of using a 
a peculiar formula for the preparation of the Cerat. Cantharidis, 
of the U. S. Pharmacopoeia, I have thought it advisable to ac- 
quaint you with it, in order that it may be given publicity if de- 
serving of it, which I take the liberty to leave to your superior 
judgment. It has no doubt frequently occurred to many that the 
cerate prepared according to the present formula, is too hard in 
consistence to be spread with facility with a spatula in winter, 
but of course in less degree in summer. 
To obviate this defect, I have been in the habit of substituting 
for a portion of the resin, an equal portion of the liniment, can- 
tharidis of the U. S. P. This T have found to render the cerate 
more homogeneous, and to avoid its objectionable hardness, and al- 
though adding slightly to its strength, I have not found this at all 
objectionable to many of the first physicians of Washington 
who have used it, but rather desirable, on account of the variation 
in the strength of the cerate arising from the quality of the flies, 
and the amount of care and attention bestowed upon its prepara- 
tion. The formula is as follows : 
# Carthar. Pulv. Ifci. 
Cera. flav. 
Adipis aa ^viii. 
Resinae « 
Linim. Canthar. aa %h. 
M. S. A. 
I add the liniment to the resin, lard and wax at the lowest 
temperature at which they are liquid, and then add the flies as di- 
rected by the Dispensatory. The above are the proportions for warm 
weather: in cold weather the quantity of liniment may be in- 
creased, say to ^vi. Any modification of this which your supe- 
rior judgment may dictate will add greatly to its value ; but it has 
not escaped me that it may occur to you, that the simple addition 
*[The writer is perhaps not aware that in the present formula of Pharm., 
1850, the consistence of this cerate has been changed to meet the difficulty 
noticed by himself in common with others.— Ed.] 
