108 
EFFECTS OF MEDICINE ON HORSES. 
By Mr. PERCIVALL. 
Argentum — Silver. 
The only form in which silver is employed medicinally is in 
combination with nitric acid. The metal is, by solution in the 
diluted acid, converted into a salt, denominated nitrate of silver ; 
formerly known by the name of the lapis infernalis, nowadays 
commonly called lunar caustic. 
From its instantaneous chemical action on the living fibre, form- 
ing with the albumen or fibrine contained therein a sort of case- 
ous compound, and in this manner effecting complete destruction 
of the surfaces to which it is applied without causing any very 
great pain, and with little or no risk of constitutional irritation fol- 
lowing, lunar caustic, in the hands of the scientific surgeon, be- 
comes a most valuable agent. By it, in numerous instances, has 
the bite of the rabid dog been rendered harmless ; by it, many an 
irritable sore is changed into a healthy one ; many an indolent into 
a healing one ; many an excrescence and luxuriance eroded down 
to a proper level. In the hands of the veterinary surgeon lunar 
caustic is capable of also being made very serviceable. I have on 
occasions, by slightly touching the orifice of the wound with it, 
closed an open joint, and corrected intractable and boggy ulcera- 
tions. I have also succeeded in healing the chancres of glanders 
by it ; and it is undoubtedly a very useful application in certain con- 
ditions of the broken farcy-bud. In solution — from a scruple even 
as far as a drachm to an ounce — it makes an excellent colly rium 
in certain stages of conjunctival ophthalmia; and it is much more 
efficacious in this concentrated form than in the diluted state in 
which surgeons have been too much in the habit of employing it ; 
the mucous membrane being capable of sustaining its action even 
better than the skin, in consequence of the coat of mucus upon it en- 
tering into chemical combination with the nitric acid of the silver, 
and thus disarming the caustic of much of its virulence. But lunar 
caustic is not so much used in veterinary medicine as it deserves 
to be. It was formerly a very expensive preparation ; and that, I 
believe, proved a formidable bar to its introduction into the veteri- 
nary pharmacy. 
As an internal remedy lunar caustic has attained a good deal of 
celebrity in human medicine. In cases of epilepsy, chorea, and 
such like nervous disorders, surgeons have conferred benefit, 
amounting in some rare instances to cure, when all other medical 
