414 
Extracts from British and Foreign Journals. 
VESICATING COLLODIONS. 
By Mr. Charles R. C. Tichborne. 
Amongst the many epispastics which have been introduced 
from time to time, cantharides have remained pre-eminent— 
their certainty, and comparative freedom from pain, being 
their special commenders. As direct and prolonged contact 
with the skin is necessary to produce a vesicle, many sub¬ 
stances have been in use as an excipient for the application of 
the vesicant. Some of the preparations in use at present are 
fluid, whilst others are applied in the form of plaster or oint¬ 
ment. In the first instance, if the desired effect is not pro¬ 
duced instauter , rubefaction is the only result., an insufficient 
amount being left upon the surface to produce a blister.. 
Vesicating collodions are preparations which, after evapora¬ 
tion, leave a thick coating upon the cuticle, containing a 
certain quantity of irritating principle : these may be con¬ 
sidered in their actions as intermediate between the fluid and 
solid preparations, combining, as they do, the properties of 
both. It is our especial vocation on the present occasion, to 
take into consideration the construction of a formula for the 
CollocUum Vesicans. This preparation, although constantly 
used by some very extensive practitioners, is far from being 
generally introduced, which may be accounted for from the 
circumstance that there is no authorised formula for its pre¬ 
paration, if we except M. Altinger’s cantharidal ether and 
collodion, one to tw r o parts of the latter for children. Each 
maker has, then, his own formula, which might be excellent, 
or vice versa, as the case may be. It will be our endeavour 
to provide a formula which shall have sufficient strength to 
produce immediate vesication, at the same time having a due 
regard to the economy of the method. To ensure prompt 
action, it is not only necessary to introduce a sufficient 
quantity of blistering material, but it is also requisite that 
the excipient, or film in which it is applied, should be per¬ 
meable enough to allow the active principle to transude freely 
through it. The tough and contractile film left by the ordinary 
collodion is almost worse than useless, as immediately on 
drying, the cantharidin at the surface and in direct contact 
alone exerts any beneficial effect; an ordinary blister might 
