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VIII. An Eajfy and Cheap Method of preparing Sal Aératus, 
(Carbonat of Pot-afh.)- By E. A. HoLryoKe, M.D. 
of Salem, Maffachu/fetts*. 
Sir Aératus, or the falt formed of vegetable alkali fatu- 
rated by fixed air (carbonic acid), is, on many accounts, fo 
ufeful, that a communication of an eafy method of preparing 
it at little or no expence may be beneficial. The following 
may therefore be acceptable, if it be not already commonly 
known. I have myfelf prepared this falt for ten or twelve 
years paft in this way, and it is now kept in our apothecaries 
fhops. 
Take a large wooden box t, bore eight or ten holes, half 
an inch in diameter, in the fide of it, juft below the lower 
edge of the cover, at nearly equal diftances all round; bore 
alfo as many holes in the’ circular bottom of the box, clofe 
to the edge of it: then take another box of the fame kind, 
but of a fmaller diameter by half or three quarters of an 
inch ; place this in the larger, and, to keep it fteady, thruft 
three or four wooden wedges between the two boxes. The 
two boxes ¢ being thus prepared, fill the inner one with the 
pureft falt of tartar, or clean well-calcined pearl-athes, or 
any clean pure fixed vegetable alkali: put its cover on the 
outer box, leaving the inner one uncovered ; fling this double 
box, thus filled, with’a cord, and fufpend it in a diftiller’s 
vat or ciftern, while the wafh is fermenting, a little above 
the liquor, or in an empty ciftern, if it has been much ufed, 
and {till retains the fixed air: let it remain in this fituation 
for fix weeks or two months, or longer if it is not wanted ; 
let it then be taken out, and the falt, now fully faturated with 
the acid, be expofed to the fun and air to dry. 
The falt thus. prepared does neither efflorefce nor deliquefce 
* From the American Medical Repofitory. 
+ I make ufe of a common cylindrical box, about nine or ten inches 
jn diameter, and between five and fix inches deep. 
{ The defign of the outer box is merely to prevent any Cuft or dirt 
from getting into the-falt, while the holes in it fuifer the fixed air to be 
frecly admitted. ‘ 
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