Fenner's Complete Formulary - Southwest School of Botanical ...

"The dimensions of such a percolator, conveniently holding 500 grammes of powdered
material, are preferably the following: Length of body, fourteen inches (36
centimetres); length of neck, two inches (5 centimetres); internal diameter at top, four
inches (10 centimetres) ; internal diameter at beginning of funnel-shaped end, two and
one-half inches (6.5 centimetres) ; internal diameter of the neck, one-half inch (12
millimetres), gradually reduced at the end to two-fifths of an inch (10 millimetres). It
is best constructed of glass, but, unless so directed, may be constructed of a different
material.
"The percolator is prepared for percolation by gently pressing a small tuft of cotton
into the space of the neck above the cork, and a small layer of clean and dry sand is
then poured upon the surface of the cotton to hold it in place.
"The powdered substance to be percolated (which must be uniformly of the fineness
directed in the formula, and should be perfectly air-dry before it is weighed) is put into
a basin, the specified quantity of menstruum is poured on and it is thoroughly stirred
with a spatula, or other suitable instrument, until it appears uniformly moistened.
The moist powder is then passed through a coarse sieve—No. 40 powders, and those
which are finer, requiring No. 20 sieve, whilst No. 30 powders require a No. 15 sieve
for this purpose. Powders of a less degree of fineness usually do not require this
additional treatment after the moistening. The moist powder is now transferred to a
sheet of thick paper and the whole quantity poured from it into the percolator. It is
then shaken down lightly and allowed to remain in that position for a period varying
from fifteen minutes to several hours, unless otherwise directed; after which the
powder is pressed, by the aid of a plunger of suitable dimensions, more or less firmly,
in proportion to the character of the powdered substance and the alcoholic strength of
the menstruum; strongly alcoholic menstrua, as a rule, permitting firmer packing of
the powder than the weaker. The percolator is now placed in a position for percolation,
and, the rubber tube having been fastened at a suitable height, the surface of the
powder is covered by an accurately fitting disk of filtering paper, or other suitable
material, and a sufficient quantity of the menstruum poured on through a funnel
reaching nearly to the surface of the paper. If these conditions are accurately
observed, the menstruum will penetrate the powder equally until it has passed into
the rubber tube and has reached, in this, the height corresponding to its level in the
percolator, which is now closely covered to prevent evaporation, and the apparatus
allowed to stand at rest for the time specified in the formula.
Fenner’s Complete Formulary - Part I-II - MISCELLANEOUS FORMULA - Page 40
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