ON THE PREPARATION OF TINCTURES. 
539 
In describing this process, I shall refer to the use of the very convenient 
glass percolator made by the York Glass Company. 
A piece of straining-cloth having been tied over the lower end of the coni¬ 
cal vessel at (A), a layer of white sand, about half an inch thick, is put on the 
strainer to form a filter-bed, and over this is laid the powdered ginger, which, 
as it is introduced, should be well rammed down with a wooden rod, or other 
suitable instrument. Having thus introduced the ginger (B) to the extent 
•of, say a pound, and carefully packed it, so that it shall be equally compressed 
in all parts, and free from any loose or vacant spaces, a layer of sand (C) may 
be put over the surface of the ginger to prevent it from being disturbed when 
the spirit is introduced. A cork shive is now 
introduced, to facilitate the pouring in of the 
spirit without disturbing the filter-bed. The 
spirit is poured by means of a guide-rod on 
to the cork, and spreading over the powder 
forms a column (D) above it, the cork floating 
and dispersing the stream as the spirit rises. 
A pint of rectified spirit may be used for this 
purpose, and this, when introduced, should 
be gradually and equally absorbed by the 
ginger, passing downwards and forming a vi¬ 
sible line, which affords a good indication of 
how far the packing of the ginger has been 
dexterously performed. If the powder has 
been well packed and equally compressed, 
the line as it descends will form an even and 
horizontal ring round the vessel; if, on the 
other hand, one part of the powder is les3 
compressed than another, the spirit will pass 
there more quickly than elsewhere, and the 
line will be uneven or not horizontal. The 
spirit in thus percolating may occupy about 
five minutes in passing through a column 
of an inch in depth. When it has passed 
to the bottom, and the whole of the powder 
has absorbed as much spirit as it is ca¬ 
pable of holding, the percolation may be either suspended or proceeded with 
at once. In this instance the latter course may be adopted, but it is 
sometimes considered desirable to suspend the percolation for a short time, or 
to slacken the flow of the liquid, and the apparatus admits of adjustment so as 
to accomplish these objects b} r a very ingenious, simple, and economical con¬ 
trivance, which constitutes the peculiar feature in this percolator. The lower 
end of the conical vessel in which the percolation is effected is ground very 
accurately into the mouth of the receiver, and the glass stopper is in like 
manner ground accurately into the mouth of the conical vessel. It is obvious 
that these being fixed in their places and fitting air-tight, the passage of the 
liquid from the upper to the lower vessel would be prevented bv the pressure 
of the air below, and the resistance to exhaustion exerted above the liquid; 
but this impediment would at once be removed if air could escape from 
the lower vessel, and could at the same time enter the upper vessel as the 
percolation proceeds. How provision is made for allowing or stopping the 
passage of air by two grooves cut in the glass, as shown at E E. One of these 
grooves is cut in the mouth of the vessel, and the other in the stopper that 
fits into it. Neither of the grooves extends more than halfway through the 
stoppered part, the one passing through the upper, and the other through the 
York Glass Company's Percolator. 
