26 PHILIPPINE RESINS, GUMS, AND OILS 
« 
TABLE 3.—Per cent of substance dissolved from 10 grams of resin by 100 
cubic centimeters of solvent. 






| 
Temper- 
ature 
Solvent. Per cent.| used to 
expel 
solvent. 
SG 
Bthylalecohollss +9 2 8505 Ses - a eae Se ee ee re 8S eee ae 95 130 
WecAmy ll ale Oh O) tics a Seem aa a a ee, eee on ae 97 | 150-155 
Wither cere nae ay ok ee wee ee Se Sea = re ee SS Pa a eee ae 75 120 
FegsrOinie = 32 22 Os Sse, Ce ae eae oe ees 2 ae ee eee 32 1380 
IBen Zee? oe os a ae Se a aa re ga ce ee 50 | 185-140 
Turpentine Sect ees seo eke I ahs i SR eee ee se ee 46 | 170-175 | & 

OXIDATION OF MANILA COPAL 
The absorption of oxygen from the air appears to be a prop- 
erty common to all complex resin acids. Brooks * investigated 
the oxidation of Manila copal by air and summarized his re- 
sults as follows: 
1. Manila copal rapidly absorbs oxygen from the air. The oxidation 
is accompanied by the formation of organic peroxides, an increase in the 
Koettstorfer number, and evolution of small quantities of carbon dioxide, 
formaldehyde, formic acid, and hydrogen peroxide. 
2. The resin acids of Manila copal, when separated from the terpenes 
occurring in the natural resin, undergo oxidation by the air. i 
3. The evolution of carbon dioxide from Manila copal and colophony is 
probably due to the formation of organic peroxides and their subsequent 
decomposition. 
4. The increase in the Koettstorfer number obtained by prolonged di- 
gestion with alcoholic potassium hydroxide is not due to oxidation during 
the course of the experiment, but is probably caused, at least in part, by 
the breaking down of lactones and organic peroxides. Samples which have 
been exposed to the air give up carbon dioxide and formic acid to the 
alkaline solution in the Koettstorfer determination and cause the recovered 
resin to show lower Koettstorfer numbers than the initial values. 
5. Formaldehyde has heretofore not been noted among the products of 
the oxidation of organic substances by the air. I have found it among 
the products of the atmospheric oxidation of Manila copal. 
6. The oxidation of Manila copal by the air is accelerated by SunCee 
- 
Ingle + examined Manila copal to ascertain the effect of ex- 
posing it to the air. The material was finely ground and ex- 

* Brooks, B. T., Oxidation of Manila copai by the air. Philippine Journal 
of Science, Section A, Volume 5 (1910), page 219. 
+ Ingle, H., Some notes on gum resins. Journal of the Society of , 
Chemical Industry, Volume 31 (1912), page 272. 
