314 
PHARMACEUTICAL MEETINGS. 
page S9,) and is also noticed by Soubeiran, (Traite de 
Pharm., tome 1st, page 72.) It consists in suspending the 
substance to be exhausted on a porous diaphragm or sieve, 
near the surface of the menstruum, where, as the particles 
of fluid in contact with the substance get saturated and 
consequently heavier, they sink and are replaced by fresh 
portions, thus producing a circulatory process in the men- 
struum, which continues until either the substance is ex- 
hausted or the fluid saturated. 
This plan of operation is occasionally eligible, particu- 
larly where the quantity of menstruum is large compared 
with the bulk of the ingredient to be exhausted. It is pe- 
culiarly applicable in effecting the solution of soluble saline 
matter, as in preparing the solutions for Vallet's proto-carb- 
onate of iron, when haste is not required, and in removing 
soluble crystalline deposits from bottles by filling them with 
water and inverting them in the same fluid. 
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