48 
THE TANNINS. 
and will accomplish the purpose under any reasonable 
height of water column. This consists of a glass per¬ 
colator, A, fitted with a stopcock, C, at the lower end, 
and with a tightly-fitting rubber stopper, D, at the top; 
to a glass tube in this cork is attached a rubber tube, 
E, of any desired length, and connected with a small 
reservoir, that is arranged to be placed at variable 
heights above the percolator, and at the lower orifice of 
the latter is placed the litre flask B. The sample is 
packed in A and cold distilled water run on until it 
begins to drop from the lower end, the stopcock C 
is then closed, and under a pressure of a column of 
water one and one-half metres in height it is allowed to 
macerate for from twelve to sixteen hours; the stopcock 
is then opened, and the percolation allowed to proceed 
until one litre of liquid is obtained. The liquid should 
not be allowed to come from the percolator faster than 
in drops, and to obtain one litre should require from 
three to four hours. It is just as well to have a pinch- 
cock attached to the rubber tube E to assist in control¬ 
ling the flow of liquid. When the desired amount of 
cold infusion lias been obtained, the residue is extracted 
with hot water in a Yon Schroder apparatus or any 
other convenient vessel in order to obtain one litre of 
the hot infusion. 
THE ASSAY OF THE TANNIN INFUSION. 
For this part of the operation the following appa¬ 
ratus and chemicals are required. 
1. Permanganate Solution .—Ten grammes of pure 
potassium permanganate are dissolved in 6 litres of 
water. 
