384 
ON THERAPEUTICS. 
the amount of substance lost or destroyed will be the contrac- 
tion of* skin, and extent of the permanent blemish. 
r i he constitutional effects of caustics depend upon the 
local excitement which they occasion being sympathetically 
extended, inducing the symptoms that are ordinarily expres¬ 
sive of pain; in cases of absorption of the caustic agent, the 
characteristic action of the drug is developed, sometimes to 
a poisonous extent. 
As therapeutics, caustics are opposed to the development 
of perverted or depraved textures or functions, as in fungous 
granulation, morbid growths of all kinds, in fustulous wounds, 
and in perverted nervous action in the form of morbid sensi¬ 
bility. The removal of excess of healthy or diseased tissue is 
effected by the caustic with certainty, and usually with safety, 
as no haemorrhage follows the separation of the slough, while it 
can be applied to a surface which presents no elevation of 
sufficient extent to justify the use of the knife. The cases 
calling for the use of caustics are excessive granulations, 
which may be controlled by the occasional sprinkling over 
them of the sulphate of copper in fine powder; or by the 
judicious use of nitrate of silver round the edges of the wound 
sufficiently to allow the advance of the integument by succes¬ 
sive steps. For the destruction of warts which are too exten¬ 
sive, or too small, or otherwise inconveniently situated for the 
knife. Arsenic, mixed into a paste with honey, we have found 
very effective; a small point of the excrescence is made to 
bleed, and a little of the paste applied ; the death of the whole 
mass follows, and by sloughing the entire growth is removed. 
In the treatment of wounds which present an unhealthy 
surface, solutions of sulphate or chloride of zinc, of various 
strengths, will rectify the morbid condition. For the destruc- 
tion of fungous growths and the hard fibrous or cartilaginous 
lining of sinuses, none but the most potent agents are to be 
selected. Chloride of zinc, bichloride of mercury, and the 
undiluted mineral acids, are severe but effective remedies, in 
such cases as “canker” in the foot, “foot rot,” “'foul” in the 
foot, and “quittor.” During ulceration, and in cases of extreme 
sensibility of wounded surfaces, and even in the same condition 
present often in irritation of the skin without any abrasion, 
a strong solution of nitrate of silver, is of marvellous efficacy; 
sponged over the part it lessens the nervous excitement, 
diminishes pain, and induces a healthy circulation ; among 
caustics none is more controllable nor more perfect initsaction. 
Caustics, indeed, as a class are of extensive application. 
Whenever it is desirable to alter the physical or chemical 
condition of a part of the organism, to destroy diseased 
