72 CINCHONA BARKS. 
oxalic acid are then added, and the mixture shaken vigorously and 
frequently during half an hour. The mixture, while intimately 
well mixed, is poured on to a well-wetted double filter of 12 centi- 
meters (4.75 inches) diameter, and the aqueous solution filtered 
from the amylic alcohol into a tared capsule of 10 centimeters (4 
inches) diameter. The filter and contents are washed with 5 
cubic centimeters (80 minims) of water, applied drop by drop from 
a pipette to the edges of the filter and surface of the amylic alco- 
hol. The amylic alcohol is then poured back into the flask, over 
the edge of the filter and funnel, rinsing the last portion in with a 
few drops of water. 10 cubic centimeters (160 minims) of water. 
and 1 cubic centimeter (16 minims) of normal solution of oxalic 
acid are now added, again shaken vigorously for a minute or two, 
and the whole returned to the wetted filter, and the aqueous portion 
filtered off into the capsule with the first portion. The amylic 
alcohol is again returned to the flask, and the washings repeated 
with the same quantities of water and normal oxalic acid solution. 
When this has drained through, the filter and contents are 
washed with 5 cubic centimeters (80 minims) of water, applied 
drop by drop by drop from a pipette. The total filtrate in the 
capsule is evaporated on a water-bath, at a low temperature, until it 
is reduced to about 15 grams (241 grains) and this transferred to 
a flask of 100 cubic centimeters (3.3 fluidounces) capacity, rinsing 
the capsule with 5 cubic centimeters (80 minims) of water, and 
adding this to the contents of the flask. 20 cubic centimeters (0.66 
fluidounce) of purified chloroform are now first added, and then 
6.1 cubic centimeters (98 minims) of normal solution of sodium 
hydrate, and shaken vigorously for five minutes or more. While 
. still intimately mixed by the shaking, the mixture is poured upon 
a filter of 12 centimeters (4.75 inches) diameter, well wetted with 
water. When the aqueous solution has passed through, leaving 
the chloroform on the filter, the filter and chloroform are washed 
with 5 cubic centimeters (80 minims) of water, applied drop by 
drop. The chloroform solution is then, by making a pin-hole in 
the point of the filter, transferred to another filter ig 10 centimeters 
(4 inches) diameter, well wetted with chloroform, and placed over 
a tared flask of 100 cubic centimeters (3.3 fluidounces) capacity. 
The watery filtrate is washed through into the chloroform-wet 
filter with 5 cubic centimeters (80 minims) of purified chloroform, 
and when this has passed through into the flask, the chloroform- 
wet filter is also washed with 5 cubic centimeters (80 minims) of 
chloroform, applied drop by drop to the edges of the filter. When 
the whole chloroform solution of alkaloids is collected in a flask, 
