74 CINCHONA BARKS. 
bark. These weights multiplied by 20 will give the percentage 
of ether-soluble alkaloids, and of quinine.” 
Another process, which is essentially that adopted by the Puar- 
MACOPEIA GERMANICA (editio altera), but since improved by a slight 
modification, is as follows:— 
III. Twenty grams of the finely-powdered bark are repeatedly 
and actively agitated with a mixture of 10 grams of ammonia 
water (spec. grav. 0.960), 20 grams of alcohol (spec. grav. 0.830 
to 0.834), and 170 grams of ether (spec. grav. 0.724 to 0.728), 
and, after standing for a day, 120 grams of the clear liquid are 
poured off. After the addition of 30 cubic centimeters of one- 
tenth normal hydrochloric acid (containing 3.65 grams HCl in 1 
liter) to the decanted liquid, the ether and alcohol are completely 
removed by distillation or evaporation, and, if necessary, so much 
hydrochloric acid added as is required to acidulate the solution. 
This is then filtered, and the cooled liquid mixed with 3.5 cubic 
centimeters of normal solution of potassiuny or sodium hydrate. 
After the alkaloids have been separated, the solution of alkali is 
added to the clear supernatant liquid until no further precipitate is 
produced. The entire precipitate is finally collected upon a filter, 
and gradually washed with a little water until the drops of liquid 
escaping from the filter, when allowed to fall upon the surface of 
a saturated neutral solution of quinine sulphate in cold water, no 
longer produce a turbidity. After being allowed to drain, the 
alkaloids are gently pressed between bibulous paper, then dried by 
exposure to the air sufficiently to admit of bringing them into a 
glass capsule, in which they are placed over sulphuric acid, and 
finally completely dried in a water-bath. The weight of the dry 
alkaloids, which, according to the requirement of the Pharmacopeeia 
Germanica, should amount to not less than 0.42 gram, or 3.5 per 
cent., does not relate to 20 grams of the powdered bark, but only 
to 12 grams of the same, since only 120 cubic centimeters of liquid 
were decanted. 
The alkaloids, which by this method are obtained somewhat less 
pure than by the preceding, may again be dissolved in hydro- 
chloric acid, precipitated by alkali, then taken up by chloroform or 
ether, and, after the evaporation of the latter, weighed.’ 
The method of De Vrij, as adopted by the Unrrep SratEs 
Puarmacopata (Sixth Decennial Revision, 1880), for the assay of 
Cinchona barks, is as follows :— _ oe ea 
1 Compare Prollius, Archiv, der Pharm., e : (1881), p. 86; Biel, Zdzd, 220 ( 1882), Pp: 
355; and H. Meyer, /é7d, 220, (1882), pp. 721, 812. The weight of the residue remain- 
ing upon the evaporation of the ether corresponds approximately to the amount of 
quinine, — . 
