224 BROOKS. 



storfer number of 187. This sample gave a positive test for peroxides 

 and gave off carbon dioxide on heating to 100°. 



Henriques ,s made a series of similar experiments on colophony with the object 

 of determining whether or not esters were present. The "acid numbers" of the 

 recovered resins were in every case lower by 6 to 8 units than the values obtained 

 for the original samples. 



The above table also brings out the well-known fact that prolonged 

 digestion of resins in alcoholic potash yields high Koettstorfer numbers. 

 According to Lewkowitsch 10 abnormally high values may be obtained by 

 prolonged digestion even in the cold. The series of determi-nations made 

 in the small sealed flasks also show conclusively that the higher values 

 are not caused by atmospheric oxidation during the course of the experi- 

 ment, as was suggested by Worstall. Several determinations were made 

 in an atmosphere of hydrogen with the same result. Two determinations 

 were made on separate portions of the same sample, the only difference 

 being that a current of hydrogen was passed through one flask and a 

 stream of air, free from carbon dioxide, through the other. An increase 

 of 15 units was observed in the Koettstorfer number of the latter and 

 an increase of 13.5 units in the former case. 



Lewkowitsch says that the changes produced by prolonged digestion in alkalies 

 point to "gradual degradation" of the resin. Fahrion 20 and others have suggested 

 that lactones may be present, which are formed by rearrangement of peroxides, 

 similar to the reactions which Baeyer and Villiger 21 found in the case of the 

 peroxides of camphor, menthon, tetrahydrocarvon, and ketoeyclohexane. Accord- 

 ing to this theory the lactones present in the resins are slowly decomposed by 

 alkalies and give rise to the gradually increasing Koettstorfer numbers. 



THE INCREASE IN THE KOETTSTORFER NUMBER OF MANILA COPAL CAUSED 



BY AUTOXIDATION. 



A freshly powdered sample of Manila copal was found to have the 

 Koettstorfer number 157. About 85 grams of this sample absorbed 135 

 cubic centimeters of oxygen during the first fourteen hours after powder- 

 ing. After standing exposed to the air for four months the Koettstorfer 

 number, determined in the same manner, was 182. Another sample in- 

 creased about 35 units during a period of eight months, having a final 

 Koettstorfer number of 210. The differences observed in these cases are 

 considerably greater than in the acid numbers recorded by Worstall. 22 

 Although the so-called acid numbers and the Koettstorfer numbers are 

 strictly comparable, it is probable that the generally higher temperature 



18 Ghent. CentraJbl. (1899), 2, 151; Chem, Rev. d. Fett. u. Earz-Ind. (1899), 

 6, 106. 



"Analyst (1901), 26, 37. 



■"Ztschr. f. ang. Chem. (1907), 20, 356. 



21 Ber. d. deutschen chem. Ges. (1899), 32, 3625. 



- Loc. cit. 



