70 CINCHONA BARKS. 
of displacement should be continued uninterruptedly for nearly 
a day, but when once in progress it requires but little atten- 
tion. In order to determine whether the bark is completely 
exhausted, a few drops of the ether, falling at C, are collected in a 
test-tube, and mixed with about an equal volume of a solution of 
potassio-mercuric iodide (0.332 gram potassium iodide, and 0.454 
gram red mercuric iodide, in 100 cubic centimeters of water); no tur- 
bidity should occur if the process of extraction has been sufficiently 
long continued. When this is accomplished, 36 cubic centimeters of 
one-tenth normal hydrochloric acid (3.65 grams HCl in 1 liter) are 
added to the ether in the flask X, the ether distilled off, and sub- 
sequently so much hydrochloric acid added as may be required to 
impart to the liquid an acid reaction. After having cooled, the 
liquid is filtered from the separated mixture of wax, chinovin and 
chlorophyll, 40 cubic centimeters of one-tenth normal sodium 
hydrate solution (4 grams NaOH in 1 liter), are added, and the 
whole allowed to repose until the precipitate has subsided, and the 
supernatant liquid has become perfectly clear. Sodium hydrate is 
then gradually added to the liquid as long as a precipitate con- 
tinues to be produced, for which purpose a solution of the spec. 
grav. 1.3, is the most serviceable. The precipitated alkaloids are 
afterwards collected on a filter, and gradually washed with a little 
cold water, until a few drops of the washings, when allowed to flow 
on the surface of a cold, saturated, neutral, aqueous solution of qui- 
nine sulphate, cease to produce a turbidity. The drained precipitate 
contained on the filter is then gently pressed between bibulous 
paper, and dried by exposure to the air. It may afterwards readily 
be removed from the paper without loss, and, after thoroughly 
drying upon a watch-glass over sulphuric acid,* is finally dried at 
100° C (212° F.), and weighed. The weight of the precipitate, 
multiplied by 5, will give the total percentage of mixed alkaloids 
in the bark. 
If it is desired to accomplish the estimation of the alkaloids with 
more simple apparatus, the ether may be substituted to advantage, 
either wholly or in part, by higher boiling liquids; e. g., by Toluol 
(boiling point, 111° C.), Xylol (137°), or Amylic Alcohol (129°). 
A methodsof this description has been furnished by Squibb,’ and is 
very worthy of recommendation. | 
II. Squrss’s MetHop :— 
“To 1.25 grams (19.29 grains) of well-burnt lime, contained in 
* By operating in this way, the agglutination of the precipitate is avoided 
elimination of the water Gee 6 Pa ee and the 
* Ephemeris of Materia Medica, Pharmacy, ete., Brooklyn, N. Y., 1882, pp. 78, 105. 
