boullay's filter, etc. 
15 
Syrup of Rhatany made with 8 ounces to the pint. 
" Buchu " 4 " •< 
« UvaUrsi " 4 " " 
" Digitalis " 4 " " 
" Boneset " 4 " " 
u JBark " 4 " " 
<tf Pareira brava 4 " " 
Likewise rhubarb and others of officinal strength. 
Thus far my remarks have had reference only to the applica- 
tion of the displacement system to vegetable powders. One 
particular use to which it is applicable, is that of filtering 
resinous substances. In the different treatises upon displace- 
ment, I have not seen any mention of its having ever been 
applied to substances of this character, or the remotest allu- 
sion to its possibility. It may have been deemed impractica- 
ble, from the homogenous nature of the resins, and tendency 
of their particles to conglomerate when brought in contact 
with alcohol. I was led to try this species of filtration by 
reason of the difficulty I had encountered in producing a 
clear solution of resin, in making some peculiar kinds of 
varnish which I had frequent occasion to prepare. Hereto- 
fore, by the process resorted to, the operation cost me con- 
siderable time, trouble, and attention. I had been accustomed 
to put the ingredients along with the alcohol into an alembic, 
and effect a solution by heat ; as filtration through paper cr 
other material was out of the question. I then put the vessel 
aside to allow a deposition of the impurities; this took place 
gradually, but demanded a long time for its completion, 
when I decanted my clear solution. This operation, every 
one knows, is attended with danger if not done in a water- 
bath, through risk of combustion, in the event of a fracture of 
the vessel. Now, instead of operating by digestion, or any 
previous maceration, I commence by bruising coarsely my 
ingredients, after which I mingle with them about one-half 
their weight of coarse sand, clean and white, if intended for a 
solution having but little color, and with this some clean cut 
straw. Then in a large tin funnel placed in a bottle or other 
