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PERMANGANATE OP POTASSA. 
The manganates of potassa and soda both pass into per- 
manganates spontaneously when in aqueous solution. The 
salts of permanganic acid are of a fine red or purple hue, 
more permanent than the hydrated acid ; they deflagrate 
with combustibles, all are soluble in water, and some are 
deliquescent. In solution they are decomposed by ammonia, 
sulphuretted hydrogen, sulphurous and phosphorous acids, 
and by contact of organic matter. In all probability, their 
efficacy as therapeutic agents is owing to this circumstance. 
Dr. Gird wood considers permanganate of potassa to be a 
deodorant , an escharotie , and stimulant; possessing all these 
three qualities when topically applied. It may be used 
either in powder, being sprinkled over the sore, as a lotion, 
or injection. He has found it most efficacious in cases of 
cancer, in sloughing and old chronic ulcers, and in caries ; 
all of which demand the employment of an escharotie and 
disinfectant combined, and likewise in warty excrescences. 
He adds, “ I have generally used the remedy as a lotion, in 
the proportion of twenty grains to a pint of water; but 
although I have not found it necessary, for the purposes I 
have generally required, to use it in a stronger form, I would 
recommend, when it is wished to destroy masses of cancer- 
ous growth, its use in the solid form, either as a powder, as 
I have done, or in a mass, as the sulphate of copper or other 
caustics. The lotion supersedes all the charcoal, yeast, and 
carrot poultices. Let this simple solution — make it as weak 
as may be thought requisite to effect the object — -two to 
twenty grains, or more if liked— be used on a piece of lint, 
instead of any of these applications. The permanganate of 
potash is more useful than any of the other compounds of 
manganese and potash as a caustic or deodorant. The per- 
manganic acid contains more oxygen than the manganic. 
The permanganic acid has the composition Mn 2 0 7 , whilst 
. the manganic acid has a composition MnO s . 
As the escharotie action of these bodies, as well as their 
deodorant quality (a quality which has been long known to 
chetnists), depends on the ease with which they part with the 
ox)^en with which they abound, clearly that preparation 
wfiLh yields the larger quantity of oxygen must be preferable : 
this as- the permanganic acid as permanganate of potash. 
I have found it a most desirable deodorant. A teaspoonful 
of the substance powdered, added to a tablespoonful or two 
of water, just enough to moisten it well, and sufficient to 
cover the surface of a flat dish — a dinner plate, for example, 
being used for the purpose — giving a broad surface for ab- 
sorption, and this plate placed under the bed, or anywhere 
