boullay's filter, etc. 
11 
The quantities of extract designated in the above synopsis, 
as having been furnished by decoction and maceration, are 
greater than would be produced by the common mode, as 
these gentlemen, after depriving the substance of as much 
liquid as pressure would allow, treated it by displacement, not 
to lose the balance retained. The results of these experi- 
ments tend to convince the most sceptical that the product by 
displacement is most abundant. Some of them 1 repeated, 
and though I find some little discrepancies in the proportion- 
ate quantities afforded, yet they were in the main correct. 
It must be borne in mind, that the treatment of substances 
in large quantities does not always produce equally favorable 
results with minor experiments, neither does this method, 
applied to one kind, answer advantageously with all others. 
This depends in a great measure upon management. Attend 
to Boullay. 
" The application of this method demands a special and pro- 
found study ; the manipulation proper to one may not suit 
another. By a little variation, one who is careful may draw 
excellent results, while an unskilful person may miscarry 
with the most easy substances. Gentian, for example, swells 
so when wet with water, and the liquid becomes so thick, that 
the running is almost impossible. Express this tincture, and 
the remainder becomes easy to wash. Weak alcohol and 
wine traverse it much better. At the first washing, squill swells 
almost to a paste. The second no longer produces the same 
effect. Rhubarb in fine powder is with difficulty washed 
with water, because it augments considerably in volume. 
With coarse powder, the displacement is easy, and the wash- 
ing perfectly exact, by reason of the porosity of the matter. 
Space gives rise to the same remarks, more or less analo- 
gous/' 
Gentian and burdock roots, and saponaria leaves, do not 
seem to answer by this process in operating with cold water, 
though they favor it much better in the treatment by alcohol. 
According to Mr. Guillermond, sarsaparilla may be included 
in this remark. His experiments upon this root with cold 
