CHLORIDE OF ZINC AS AN ESCHAROTIC. 
197 
with a little care, can be easily circumscribed. Several years 
ago, the writer was induced to combine it with the oxide of 
zinc as a convenient vehicle for diluting, and applying it to 
a sore. 
Experience has amply proved the advantages which this 
combination possesses over those commonly recommended, 
such as flour or plaster-of- Paris ; for while with the oxide it 
remains as a powder easy of application, so as to produce a 
certain and uniform result, with the latter means it forms 
a paste of some consistence, and becomes much less manage¬ 
able. The oxide also possesses the peculiar quality of 
protecting the chloride from deliquescence, and so allows it 
to be kept for a considerable (if not indefinite) period, and 
the mixture is always ready for use. Two bottles, containing 
respectively the pure chloride, and a mixture of the chloride 
and oxide, have stood on the shelves of the writer’s library 
for about a year, and now present the following conditions: 
the first has attracted about two drachms of water from the 
atmosphere ; the second is still as pulverulent as ever. At 
first, different proportions of the ingredients were employed, 
according to the effect desired ; but subsequent experience 
has shown the advantage of keeping to one formula, by 
which more uniformity of action can be secured, and at the 
same time the remedy is as manageable as if diluted to a 
much greater extent. It consists of the dry chloride and 
oxide of zinc, accurately mixed, in equal proportions. The 
mixture may be preserved in a wide-mouthed bottle, having 
an accurately-fitting stopper. It is said that a chemical 
combination occurs between the chloride and oxide ; but, 
so far as can be decided, no great loss of activity results. 
If, then, it is desired to produce a slough, a little may be 
taken from the bottle by a silver or bone spatula, and 
<c dusted” over the surface of the sore by the aid of a piece of 
common muslin, or, if more convenient, it may be made into 
a paste with a little water, and then spread by the spatula. 
When a superficial slough is required, a slight application 
will suffice ; but to secure a deep eschar, the powder must 
be laid on to the thickness of ordinary card-board : the edges 
of the sore should be dried to the limit intended, and then 
a little ointment may be smeared on the surface as a further 
protection from the salt ; the oxide will prevent the action 
of the escharotic from spreading beyond due limits, so that 
the effect may be accurately determined. 
Chloride of zinc acts as a cauterant by, first, its power of 
abstracting water from the tissues; and, secondly, by its 
combining with the albuminous and gelatinous compounds, to 
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