210 ANALYSIS OF CHINCHONA BARK AND LEAVES. 
or the period when they are at rest, notwithstanding the bark was 
found to separate freely from the stems; therefore if these specimens 
are found to contain a larger percentage of alkaloid than those pre- 
viously submitted, this will no doubt be the most favourable season of 
the year for peeling and drying the bark. 
9. Further observation seems to establish that the plants will give 
a fair yield of bark annually from lopping and pruning, on the principle 
suggested in my letter of the 4th June, 1861. In accordance with 
this system of pruning, I removed two of the lower branches from a 
plant of Chinchona succirubra two years and five months old. The 
bark of these branches form specimens Nos. 1 and 2, and give a total 
weight of 21% tolas, or about 83 ounces of dry bark. -I expect that 
No. 1 will be valuable; No. 2 is from the very small succulent 
branches, consequently its yield in alkaloid may not be of sufficient 
value to pay the cost of preparation and transport. I am anxious that 
Mr. Howard should give the probable market value of these two 
samples of bark, in order to enable us to form an approximate estimate 
of the yearly returns from loppings and prunings, as I feel convinced 
that this will be our principal source of revenue, at least for many 
years to come, especially as the system tried experimentally of re- 
moving strips of bark from the stems of the plants has been found to 
injure their growth, and therefore cannot be profitably practised. 
Chinchona succirubra. 
No. 1. Bark from the thickest part of two lower branches of a plant 
of C. succirubra two years and five months old. This bark 
when fresh, i.e. immediately after being removed from the 
branches, weighed 37 tolas ;* one hour's drying reduced the 
weights to 32 tolas, and when perfectly dry it was found to 
have decreased in weight to 121 tolas, giving a loss of about 
two-thirds in drying. 
2. Bark from the spray or small portions of the same branches as 
No. 1. This bark when fresh weighed 40 tolas or 1 lb., in 
one hour's drying its weight was reduced to 31 tolas, and 
when thoroughly dry to 94 tolas, making the loss of weight 
in drying fully three-fourths. 7 
3. Bark from the stems of C. succirubra from plants of sixteen 
months’ growth, weighing 183 tolas of dry bark. 
* 40 tolas make 1 English pound, and consequently 24 tolas = 1 ounce. 
