750 
SOCIETY MEETINGS. 
. Another classification is (i) those used externally for the 
cure of internal diseases. These cure by revulsion, relieve pain, 
produce diaphoresis and arrest forming disease. The counter- 
irritants commonly used to produce these effects are hot appli¬ 
cations, cantharides and liniments ; (2) those used in the treat¬ 
ment of lamenesses, etc. These promote a cure by increasing 
the activity of the superficial parts and of the circulation. They 
tend to destroy the elasticity of the skin, because of a decided 
thickening, and prevent the use of the leg or obstruct motion 
because of the soreness of the skin. They also, when not too 
severe, cause hypersemia of the superficial parts and anaemia of 
the deeper structures, but when severe the inflammation be¬ 
comes deep-seated, which is proven by the fact that an increased 
amount of fibrous tissue has been found in the deeper parts of a 
leg years after the application of a severe blister or firing iron. 
Again, when animals are treated, they are given a rest from 
work, which is often an aid in curing the disease. The counter- 
irritants commonly used in the order of their importance are, 
cantharides, mercuric iodide or biniodide, actual cautery, setons 
and liniments. 
To make cantharides blister, take eight parts of lard or'vas¬ 
eline, heat to 12d 0 Fahr., and stir in one part of the pulverized 
cantharides. As excessive heat tends to destroy the active 
principle, or cantharidin, a complex animal substance easily 
broken up into simpler compounds; the vehicle should not be 
heated very hot. If applied over a very large surface, a propor¬ 
tion of 1-16 is sufficiently strong, and even then it causes irrita¬ 
tion of the kidneys and excessive diuresis, which may continue 
for a week. 
Biniodide of mercury is also mixed with lard or vaseline in 
a proportion of 1 part to 4, 6 or 8. It is indicated in such cases 
as require a more severe treatment than fly blister, and will di¬ 
minish enlargements of soft and hard structures. These two 
blisters, or the so-called mixed blister, should never be used 
together, for the action of cantharides is quicker and the exu¬ 
date it causes washes off the biniodide before it has been ab¬ 
sorbed, thereby causing a loss of material. Sometimes a little 
of the biniodide may be used every night until the skin is blis¬ 
tered, when it should be stopped until the skin heals. 
In ordinary firing, line firing is preferable, and if neatly done 
need not “mark” an animal much more than point firing. If 
the client objects to the patient being marked, fire lightly and 
apply a strong blister, but if no objection is made, it is better to 
