EXPERIMENTS ON LIVING CVNCHON2E. 
9 
succeeded in obtaining exactly the same weight of free alkaloids. After exposure the 
loss varies greatly, from 0-4 to 1 per cent. According to Pasteur there should be no 
loss of weight when the crystallizable alkaloids are converted into their isomeric crystal- 
line forms. Direct trials showed that this loss is connected with the effect of sunshine ; 
for when the bark is dried at 50° C., or in vacuo over sulphuric acid, no such loss occurs. 
No alteration in the relative amounts of quinine and cinchonidine could even be de- 
tected as the effect of insolation or artificial heat. 
The damaging effect of light is not practically of great importance in the commercial 
preparation of the bark. The dry air and fierce sun of the Neilgherries with care may 
be made to dry the green bark so rapidly that sufficient time does not elapse for any 
appreciable deterioration of quality to be effected ; nevertheless the sagacious dictum 
of Pasteur must be held to be true. 
A high temperature, or even a steam-heat, is prejudicial to the quality of cinchona- 
bark, for reasons before mentioned. The former converts part or the whole of the crys- 
tallizable alkaloids into their uncrystallizable isomers; the latter often causes a com- 
pound of cinchona-red to be formed with the alkaloids, which is decomposed with diffi- 
culty by acids. 
The following series of analyses, though conducted with special reference to economical 
results and the methods of commercial manufacture, aptly illustrate the foregoing prin- 
ciples. In all cases the finely shred bark was dried by the several methods ; the fine 
division exaggerates the difference of result. 
Bed Bark. 
Fresh bark. 
Dried at 17° C. 
in vacuo. 
Dried at 
steam-heat. 
Dried in 
current of air 
at 35°-45° C. 
Dried in 
sunshine. 
Dried in 
sunshine 
slowly. 
Total alkaloids 
Crystalline sulphates obtained . 
Comparative amounts of acid 1 
required to neutralize the 1 
alkaloids 
6-89 
6-67 
5-92 
6-64 
5-90 
5-85 
6-12 
5-98 
5-31 
5-89 
5-28 
4-78 
] 3*2 
13-1 
11-8 
13-1 
12-0 
11-6 
Mixed Crown Barks. 
Fresh bark. 
Dried at 17° C. 
in vacuo. 
Dried at 
steam-heat. 
Dried in 
current of air 
at 3tF-45° C. 
Dried in 
sunshine. 
Dried in 
sunshine 
slowly. 
Total alkaloids 
3-93 
3-92 
3-52 
3-85 
3-G3 
3-04 
Crystalline sulphates obtained ... 
3-67 
3-52 
3-01 
3-56 
3-11 
2-88 
Comparative amounts of acid 1 
required J 
7-2 
7-0 
6*6 
C-8 
6-7 
5-9 
The effects of the sun’s rays on cinchona-bark, when separated from the tree, being 
MDCCCLXXI. c 
