100 



MATERIA MPDICA. 



Fig. 26. 



Fig. 2.5 



water ; flour may be added to 

 dilute it. It should not be al- 

 lowed to remain on longer 

 than from 15 to 30 minutes ; 

 never to produce vesication. 

 Care should be taken not to 

 leave it too long on persons 

 insensible to pain, lest ulcera- 

 tion and sloughing result. 



Oil of Turpentine is a 

 powerful rubefacient ; used by 

 saturating a flannel and ap- 

 plying it to the skin ; some- 

 times produces a violent in- 

 flammation and eruption on 

 the skin. 



Cayenne Pepper may be 

 advantageously used as a ru- 

 befacient, by heating it in 

 spirits, and rubbing it over 

 the surface ; particularly ap- 

 plicable in the low forms of 

 disease. 



CLASS XVIL — ESCHAROTICS, OR CAUSTICS. 



" Substances which cause a slough by destroying the life of the part 

 to which they are applied." Some of them act directly, others indi- 

 rectly, through chemical agencies. Used to form issues or running 

 sores, to repress fungous granulations, to change the character of 

 diseased surfaces, and to open abscesses. The hot iron, or actual 

 cautery, is the most powerful escharotic ; not so much employed at 

 present as formerly ; occasionally used to arrest hemorrhage. 



The moxa is a modification of the actual cautery ; it consists of 

 small rolls of muslin soaked in a solution of chromate or nitrate of 

 potassa, and dried. When used, one end is set on fire, and the other 

 placed on the skin. It acts as a powerful revulsive ; useful in deep- 

 seated pains, paralysis, disease of spine, &c. 



Lunar Caustic. — (Argenti Nitras, U. S.) 



Made by dissolving pure silver in diluted nitric acid, evaporating, 

 mehing, and running into moulds. It occurs in cylindrical pieces, 

 enveloped in paper to protect it from the light, which decomposes it. 

 Colour, grayish-white ; taste, austere and metallic ; very soluble. As 

 a caustic, it acts through its chemical affinities for the albumen of the 

 tissue. It is a safe and excellent escharotic ; particularly useful to 

 change the character of unhealthy ulcers, whether common or spe- 



