RESINS 43 
The trees must be visited regularly to get good returns. The 
resin can be gathered at almost all seasons, but towards the end 
of the dry season the flow is very slight. Resin is collected from 
the same trees: year after year. Clover * says that he has seen 
large-sized trees on which at least ten pounds of resin had ac- 
cumulated, probably within a month. Bacon? estimates that 
mature trees will yield an average of 45 kilos per year. He 
says that he has seen as much as 382 kilos of resin on a large tree. 
This amount represented a two months flow. 
In some localities where the resin is collected, it sells for about 
50 centavos per arroba of 11.5 kilos if clean and white, but when 
dark for about 30 centavos. In larger towns the best quality 
sells for about a peso a kilo and in Manila for about 3 pesos. 
If the industry of collecting the resin were systematized, the 
cost in Manila would certainly be greatly reduced. 
Bacon ¢ collected over one hundred specimens of elemi resin 
from individual trees. 'These samples of fresh elemi resin were 
distilled 7n vacuo, the volatile oils were then separated from the 
water, shaken out with dilute alkalies, dried over calcium 
chloride, and redistilled in vacwo; only the terpene fraction was 
collected. The terpenes were then distilled at ordinary pressure. 
These results verified the conclusions of Clover that the terpene 
oils of elemi resin obtained from different trees showed great 
differences in their boiling points and especially in optical rota- 
tion. For purposes of purification and identification, the various 
distillates of elemi resin were divided into different groups ac- 
cording to their boiling points. Bacon found that these dis- 
tillates consisted largely of various terpenes such as alpha and 
beta phellandrene, dipentene, limonene, etc. He prepared va- 
rious derivatives of these terpenes, such as phellandrene nitrite, 
dipentene tetrabromide, limonene tetrabromide, etc. Judging 
from Bacon’s experiments, the best method for purifying elemi 
resin is by solution in benzene, filtering off the impurities such 
as bark and dirt, and distilling the filtrate. A white resin of 
leafy appearance is thus obtained. 
Bacon investigated nine samples of carefully purified terpenes 
from elemi resin obtained in Gumaca, Tayabas. The results are 
recorded in Table 5. 

* Clover, A. M., The terpene oils of Manila elemi. Philippine Journal 
of Science, Section A, Volume 2 (1907), pages 1 to 40. 
+ Bacon, R. F., Philippine terpenes and essential oils, III. Philippine 
Journal of Science, Section A, Volume 4 (1909), pages 93 to 265. 
t Bacon, R. F., Philippine terpenes and essentia] oils, III. Philippine 
Journal of Science, Section A, Volume 4 (1909), page 93. 
