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

percolate.
The flow of percolate maybe regulated by the rubber tube, as directed in
the officinal process; by a loose cork in the bottom of the percolator; or, if
the water-bath percolator is used, by the stop-cock. The rapidity with
which the percolate should flow, depends very much upon the nature of
the drug, and the quantity required to be obtained as compared with
the quantity of drug being percolated; for example, fluid extracts should
not be percolated so rapidly as tinctures, nor aconite as rapidly as
buchu.
With a certain class of drugs, the alcoholic or hydro-alcoholic
menstruum, with which the percolation is conducted, may be forced out
by adding water after the menstruum has disappeared from the surface
of the drug, and thereby make a saving of alcohol; but with others,
which soften or make precipitates with an aqueous menstruum, the
percolation must be conducted to the end with the same menstruum.
The menstruum remaining in the drug after percolation, may be
pressed out with a tincture press and the alcohol recovered from it by
distillation.
Drugs Difficult to Percolate.
Many drugs present difficulties to the ordinary methods of percolation
and require special treatment; this is generally given in the formulae in
which they are found ; but they may be classed in a general way as
follows :
1. Drugs that soften or make a pulpy mass upon the addition of the
menstruum, such as orange, gentian, rhubarb, squill, colocynth, etc.
Such drugs should be well moistened and macerated before packing;
they should be rather coarsely powdered and rather loosely packed, and
Fenner’s Complete Formulary - Part I-II - MISCELLANEOUS FORMULA - Page 43
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