G 
MR. J. BROUGHTON’S CHEMICAL AND PHYSIOLOGICAL 
from the precipitated compound of oxide of antimony and tannin formed in an acetic-acid 
solution, and subsequently determining the amount of antimony in the precipitate, I esti- 
mated the amount of the peculiar tannin in the juice at 2*35 per cent. No verification, 
however, could be made, as it is scarcely possible to procure this peculiar tannin in a 
pure state, from its excessive proneness to oxidation. 
The tannates of the alkaloids appear quite similar, when prepared artificially, to those 
found in the bark. When obtained as mentioned above from the barks, they are readily 
decomposed by mineral acids. They oxidize very rapidly, and form red substances, 
which, when moist, are decomposed with moderate ease by acids with separation of cin- 
chona-red, and very readily, but not quite completely, by alkalies, which dissolve the 
cinchona-red and leave the alkaloids in a coloured state. If the tannates are heated to 
100° and become quite dry, they occasionally form a red compound, which resists the 
action of dilute mineral acids even on boiling. This is a fruitful cause of inaccurate 
bark analysis, when the bark has been long dried in a water-bath previously. In such 
cases it is better to treat the bark with alcoholic potash, as recommended by I)e Vey 
(P harm. S. Trans, vol. vi. p. 50). 
Order in which the Alkaloids are formed in the living Tissues of the Bark. 
Very much light has been obtained on the order in which the natural formation of 
the cinchona alkaloids proceeds, by making periodic examinations of rapidly forming 
bark-tissues. 
When cinchona-bark, not exposed to the direct rays of the sun, is carefully removed 
in strips without injury to the delicate cambium-cells underneath, such bark is rapidly 
renewed by natural processes. The cambium immediately thickens, so that after a little 
more than a week a thin cellular layer of a light green colour has covered the wound. 
On the surface of this, light brown granulations are found which spread and thicken. 
For many months only parenchymatous cells are to be seen ; but subsequently short 
woody cells are found, which lengthen and increase in number and thus form a liber. 
The so-called resin-cells do not appear, nor have I observed any laticiferous vessels in 
this renewed bark. A true cork is, however, formed. 
Bark thus rapidly renewing has been analyzed at various intervals of the process. The 
following series is one of many ; but I quote it here because it possesses an additional 
element of precision in being a set of experiments performed on the trunk-bark of the 
same tree of C. succirubra. 
After 
four 
months. 
After 
six 
months. 
After 
ten 
months. 
After 
fifteen 
months. 
After 
seventeen 
months. 
Total alkaloids 
4*30 
5-30 
5-03 
6-00 
5-47 
Quinine 
4-20 
4-40 ' 
4-02 
3-03 
2*65 
Cinchonidine and cinchonine 
0-10 
0-90 
1-01 
2-97 
1-82 
Crystallized sulphate quinine obtained... 
0-25 
1-56 
2-20 
2-30 
3-12 
