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ON VESICATING APPLICATIONS. 
ART. LIX.— ON VESICATING APPLICATIONS. 
By Mr. Redwood. 
Read before the Pharmaceutical Society of London. 
The estimation in which blisters are held as therapeutic 
agents, and the objections which are urged against those in 
general use, seem to claim our attention to this class of reme- 
dies, with the view of establishing principles upon which their 
preparation may be improved. 
The London Pharmacopoeia contains two formulas for 
vesicating applications, under the denominations of "Emplas- 
trum Cantharidis/' and "Acetum Cantharidis;" and the 
former of these has for many years been adopted by the 
Colleges of Edinburg and Dublin, as well as by the London 
College, and constitutes the officinal blistering plaster of the 
shops. This plaster requires to be applied for about twelve 
hours, in ordinary cases, before the full effect is produced, and 
in many instances a still longer application than this is 
necessary. To meet the objection which this delay would 
sometimes offer, recourse has been had to more active and 
speedy means of producing the same effect. The Acetum 
Cantharidis is intended as an agent for this purpose, and the 
Emplastrum Cantharidis Compositum of the Edinburg College 
will come under the same class. 
These are the vesicating applications ordered in our Phar- 
macopoeias, but others are sometimes resorted to in practice. 
Boiling water offers a ready means of raising an instantaneous 
blister, which is adopted by some practitioners; and strong 
acetic acid and solution of ammonia have also been used with 
the same view. Mustard seeds, applied in the form of poultice, 
possess powerful epispastic properties, as do also the essential 
oil of black mustard seeds, and the oil of croton tiglium; and 
these, together with numerous other acrid vegetable substances, 
have at different periods been employed, either alone or in 
