124 Materia Medica. 
of turpentine, 1 oz.; hog’s lard, 4 0z.; powdered can- 
tharides, 1 oz. Mix, and spread. 
6. Very Strong Blister (counter-irritant).—Strong mer- 
curial ointment, 4 0z.; oil of origanum, 4 oz. ; finely- 
powdered euphorbium, 3 drms.; powdered cantharides, 
30z. Mix, and spread. 
7. Rapidly Acting Blister (counter-irritant).—Best 
flour of mustard, 8 oz., made into a paste with water. 
Add spirit of turpentine, 2 oz. ; strong liquid of ammonia, 
1 0z. This is to be well rubbed into the chest, belly, or 
back, in cases of acute inflammation. 
8. Sweating Blister.—Strong mercurial ointment, 2 02. ; 
oil of origanum, 2 drms.: corrosive sublimate, 2 drms. ; 
cantharides powdered, 3 drms. Mix, and rub in with 
the hand. 
9. Tincture of Iodine, which should be painted on 
with a brush daily, until it causes the cuticle to exfoliate. 
It may then be omitted for a few days, to be resumed 
after that interval. 
Caustics.—Substances capable of exerting chemical 
action on the living tissues are known as caustics, such 
action being simply burning or decomposition. The 
most familiar example is the actual or potential cautery, 
or heated iron. Chemical agents as caustic soda, caustic 
potash, and lunar caustic, or nitrate of silver, are also 
variously employed. The general use is to stimulate 
indolent wounds, repress luxuriant granulations, also 
removing tumours, or parts destroyed by sloughing, and 
arresting the flow of blood from injured vessels. 
1. Caustic’ Potash is conveniently sold in sticks or 
pencils, and requires a suitable holder for operating with 
it. Its action is prompt and powerful, but being liable 
to become fluid when exposed to the atmosphere, its 
use is sometimes limited. 
2. Lunar Custic, or nitrate of silver, is by far the most 
manageable, and effective. It is sold in pencil form, 
and also requires a holder of silver or platinum for its 
preservation. 
3- Sulphate of copper, burnt alum, verdigris, red pre- 
cipitate, and corrosive sublimate are used in powder as 
