ON VESICATING APPLICATIONS. 
3i3 
sixteen grains of the powder to one ounce of ointment. 
Boerhaave ascribes to this ointment the property of keeping up 
the discharge from a blister, without producing that irritation 
found to result from the use of ointments, containing Cantha- 
rides in their natural state. It seems, therefore, that this 
ointment is intended also as a substitute for our ceratum lyttse, 
which is a mixture of powdered Cantharides and simple oint- 
ment. 
But although it would appear that the constitution and 
properties of the blistering fly have been partially overlooked, 
or imperfectly understood, yet experience has tended to 
confirm the estimation in which this insect has long been held 
by medical men as a vesicating application. The certainty 
and safety of their operation have obtained for Cantharides 
the preference over all other vesicating substances ; and we, 
therefore, find them forming the principle ingredient of the 
blistering applications in this country, on the continents of 
Europe and America, and among the Chinese. They present 
almost a solitary exception to the fate which has befallen the 
long list of animal substances, consisting of almost every 
conceivable part of almost every known animal, which figured 
in the early history of our Pharmacopoeias. The blistering 
fly, may now, therefore be considered as fully established in 
our Materia Medica. Its employment as a medical agent is 
derived from great antiquity, but it has been doubted whether 
the ancients were acquainted with its external application as s£ 
blister. Hippocrates recommends the removal of the head, 
feet, and wings; but Galen, on the contrary, contends that the 
whole insect should be used. Dioscorides and Avicenna 
adopt the latter opinion, remarking, that the parts rejected by 
Hippocrates serve as an antidote to the venom of the insect. 
These opinions are probably entitled to but little consideration; 
excepting, inasmuch, as they show the attempts made at that 
early period to investigate the properties of this substance, 
and as it is still held in equal, if not greater, estimation as a 
remedy, the time we may devote in pursuing the examination 1 
of its active constituents will not, it is presumed, be uselessly 
Vol. vii. — No. iv. 40 
