28 



in which it is so often used, depends on its exciting a super- 

 ficial inflammation, and not, as it was once currently be- 

 lieved, on its forming a permanent bandage around the parts. 

 Indeed, though the skin for a short time after the operation 

 is corrugated and tightened, it soon resumes its natural 

 elasticity, and does not embrace the subjacent parts more 

 firmly than in health. The firing of healthy hurts, with the 

 popular idea of strengthening and bracing them up, is now 

 deservedly discountenanced, for the apparent benefits result- 

 ing from the firing are now well known to result, not from 

 the operation, but from the rest which it necessitates. It is 

 a prevalent idea that the efficiency of counter-irritants is to 

 be measured by the amount of discharge which they induce, 

 but this is by no means a general rule, for the amount of 

 the counter-irritation and of the discharge do not bear a 

 consistent relation to each other, and the only accurate 

 method of judging of the power or value of any counter- 

 irritant is by the intensity and continuance of the inflamma- 

 tion it excites. The agents which decompose tissue, beside 

 the hot iron are : 



Sulphuric acid. 



Nitric acid. 



Nitrate of silver, &c. 

 These and other caustics act in a similar manner. The 

 milder counter-irritants are called rubefacients and vesicants, 

 which are treated of elsewhere in this work. 



EXTERNAL REMEDIES CHIEFLY USED IN VETERINARY 

 PRACTICE. 



Refrigerants. — Agents which diminish the morbid heat 

 of a part : 



Solution of acetate of lead. 



Solution of diacetate of lead. 



Common salt. 



Cold water. 

 Discutients. — Agents which repel indolent tumours : 



Hydroclorate of ammonia. 



Camphor. 



Compounds of Iodine. 



Soap Liniment. 

 Rubefacients. — Agents which cause redness of the skin 

 without blistering : 



Liniment of ammonia. 

 " tar. 



