ON CANTHARIDIN AND ITS PREPARATIONS. 
229 
3. Collodium vesicans seu cantharidale. 
Ether cantharidalis and gun-cotton in substance or solu- 
tion (collodium) offer a very remarkable vesicant. The ol. 
cantharid. operates as blister, and the ether rapidly evapo- 
rating, the collodium dries within a few moments and forms 
a coating. 
The formula given by Dr. Ilisch in St. Petersburgh, the 
inventor of the collodium cantharidale, has already appeared 
in the Pharmaceutical Journal, for September, 1S49. Its 
efficacy has been proved by repeated experiments made by 
Balbiani and Basse. — Pharmac. Central Blatt, 1S49, 
No. 7. 
These statements I must correct in so far, that by the 
above-mentioned operation a saturated solution of cantha- 
ridin in ether with green oil, and waxy resin — viz., the ol. 
cantharidum viride, is obtained, and not of cantharides ; 
there is also no use in employing acetic ether, since sulphu- 
ric ether fully answers the purpose. 
Dr. Rapp, who first introduced the collodium cantharidale 
into Germany, expresses himself in the following manner : 
f*. Recently medicinal substances have been combined with 
collodium for endermic application. This object can only 
be obtained by volatile substances, which combine with 
collodium, and readily dry, but which, notwithstanding 
their volatile nature, are still absorbed under the coating of 
collodium and act upon the epidermis. Such a substance 
is cantharidin ; this liquid thinly applied with a brush upon 
any part of the body, dries in a few seconds, and protects 
this part with a coating like goldbeater's skin. The skin 
surrounding the periphery of the painted place reddens in 
children within two or three hours, with adults within five 
or six hours, accompanied by a burning sensation : gradu- 
ally the coating, consisting of collodium, rises, and after a 
few hours a blister is formed, which extends a few lines 
beyond the whole periphery. On this part, which was not 
covered with collodium, the blister is opened ; the collodium 
