CORROSIVE SUBLIMATE. 101 



cific; the best application for ulcers of the cornea ; also to inflamed 

 tonsils. Sometimes a concentrated solution is preferred. The weak 

 solution is an admirable stimulant application, as already noticed 

 under the head of Tonics. 



Pot ASS A, U. S. 



Common caustic^ Lapis infernalis, — Chemically a hydrate of 

 potassa ; made by adding quicklime to a solution of carbonate of po- 

 tassa, and evaporating the resulting solution to a proper consistence, 

 and then pouring into proper moulds. Occurs in cylinders of a gray 

 colour; very deliquescent; powerfully alkaline; very soluble. A more 

 powerful caustic than nitrate of silver ; apt to extend its effects, and 

 consequently not so safe ; used chiefly to form issues, which is best 

 eflfected by rubbing a moistened stick of potassa over a piece of 

 sticking plaster, applied to the skin, and having a hole in it of the 

 size of the intended issue; sometimes used also to open abscesses, 

 -xind to destroy poisoned surfaces. The strong solution sometimes 

 applied to the spine in tetanus. 



Dried Alum. — (Alumen Exsiccatum, U. S.) 



Commonly named burnt alum ; prepared by heating alum until 

 deprived of its water of crystallization ; a dull-whitish powder; a 

 mild escharotic ; used to repress fungous granulations. 



Sulphate of Copper. 



Usually applied in the solid form ; in which state it forms the best 

 remedy in granulated conjunctivitis. A strong solution, useful in 

 ca7icrum, oris ; the weaker solution a good stimulant, — as mentioned 

 under the head of Tonics. 



Arsenic. — (Acidum Arseniosum, U. S.) 



Procured in smelting the ores of arsenic; of a milk-white colour; 

 vitreous fracture ; transparent within, but becomes opaque on expo- 

 sure ; has no odour ; taste, faintly sweetish ; powerfully poisonous ; 

 soluble in water and alcohol. A dangerous escharotic from liability to 

 absorption ; used chiefly in cancerous sores; also in lupus and onychia 

 maligna ; should always be very much diluted before applying it. 



Corrosive Sublimate. 



A powerful escharotic in the undiluted state, but seldom thus em- 

 ployed. A weak solution used as a gargle in venereal sore throat, 

 and as a lotion in chronic skin diseases ; recommended in onychia 

 maligna, mixed with equal parts of sulph. zinc. More fully de- 

 scribed under the head of Mercury. 



The Mineral acids are all powerfully caustic in the undiluted 



form ; not used as such, however, but employed, suflaciently diluted, 



as stimulant washes to indolent ulcers. 



9* 



