ON BLISTERING CLOTH. 
39 
The pitch, thus purified, is melted in an earthen vessel 
over a gentle fire, with the wax ; the cantharides, the oil, 
and the essence of turpentine are then added ; when the 
mixture is well stirred, a small quantity of the plaster is 
thrown into cold water and kneaded ; if it be neither too 
soft nor too brittle, it is then spread on the glazed side of 
some oil-cloth with a plaster-iron slightly heated. 
The quantity of wax, oil, and essence, may be varied 
according to the quality of black pitch employed, so as to 
give the plaster a consistence suitable for its being spread 
on cloth. Copper vessels should never be used for pre- 
paring those medicinal compounds of which wax is an in- 
gredient ; the plaster should be melted in a glazed earthen 
vessel. The cantharides are added by means of a sieve, so 
as to divide the particles, and prevent their collecting into 
lumps. It is convenient in sending out the blistering-cloth, 
to cut a piece of oiled paper of the same size, and lay this 
over the surface of the plaster, to prevent its adhering to 
the envelope. 
These vesicatories should never be camphorated with a 
solution of camphorated ether, but rather with camphor 
finely pulverized, and for this purpose the blistering-cloth 
should previously be slightly warmed. 
Of all the formulae published for blistering-plaster, there 
are none, in my opinion, more easy in application, and that 
will keep in a better state of preservation than this. — 
Fharm, Journ. from Journ. de Pharm, 
