DESTRUCTIVE DISTILLATION OF MANILA COPAL. 217 



of fused Madagascar copal was investigated by Coffigner, 40 who noted a decided 

 decrease in its solubility in alcohol and increased solubilities in ether, benzene, and 

 chloroform. 



A sample of Manila copal was heated slowly to 300° and kept at that 

 temperature until it had lost 20 per cent of its weight. The solubility 

 of the melted resin was determined as before. 



Table II. — Per cent of substance dissolved from 10 grams of melted copal by 

 100 cubic centimeters of solvent. 





Solvent. 



, Per cent 

 of copal 

 dissolved. 



Ethyl alcohol 





72 







. ' 49 







_ 45 





The solubilities of this sample of melted copal in benzene and tur- 

 pentine, in the above proportions, are about the same as those of the 

 unheated resin. However, these factors for fused resin depend very 

 much on the temperature and the duration of the heating. So-called 

 superfusecl copal is quite soluble in benzene and turpentine. 



When small proportions of solvent to resin are employed, the solubil- 

 ities are strikingly different from those given above. Samples of Manila 

 copal which had been heated to about 300° to 320° were completely 

 dissolved in small quantities, one to two parts, of ligroin, benzene, or 

 turpentine, whereas unheated copal could not be so dissolved. The 

 amount of unheated resin dissolved by these solvents is, roughly, in 

 direct proportion to the amount of solvent used, until all but the more 

 insoluble, flocculent matter mentioned above has gone into solution. 

 However, the amount of fused resin dissolved is not even roughly pro- 

 portional to the amount of solvent used. In fact, when a perfectly 

 clear, homogeneous solution of fused resin in one to two parts of tur- 

 pentine, ligroin, or benzene is diluted with the same solvent, the resin 

 is partially precipitated. Copal which has been fused for several hours 

 at about 300° will form clear, homogeneous solutions with larger pro- 

 portions of these solvents than resin which has been so treated for only a 

 short time. 



One specimen of copal was heated for eight hours at a temperature 

 of about 320°. The resulting mass was rather soft at 30° and dissolved 

 completely in five times its weight of benzene and almost no precipitate 

 was obtained on diluting. This superfused resin apparently consisted 

 largely of resin oil together with a little resinous matter and charred 

 substance. It had about the same consistency as a synthetic mixture 

 containing 50 per cent resin and 50 per cent resin oil. 



10 Bull. Soc. chim. Paris (1906), 35, 762. 



