216 



BROOKS. 



THE BEHAVIOR OF MANILA COPAL IN SOME OF THE COMMON SOLVENTS. 



The solubilities in several of the more common solvents of Manila 

 copal, as it comes into the market, have been determined. Those of 

 four commercial grades of the resin were found to be practically the same 

 in each given solvent. A sample which had been heated to 300° was 

 taken. When large proportions of solvents were used, the solubilities 

 in ligroin, benzol, and turpentine appeared to be about the same as for 

 unheated copal and in alcohol this factor was markedly less. 

 ■ The method was as follows : 



One hundred cubic centimeters of the solvent were taken to 10 grams of the 

 powdered resin and the whole boiled under a reflux condenser for one-half hour. 

 About 30 cubic centimeters of the clear, hot solution were then decanted into a 

 tared evaporating dish and weighed. This was then evaporated in an atmosphere 

 of carbon dioxide. From the weight of resin found in this way the p,er cent which 

 had gone into solution was calculated. In the case of ethyl alcohol, amy! alcohol, 

 and ether, all of the resin appeared to go into solution with the exception of a 

 little flocculent substance which remained undissolved even in the presence of 

 a large excess of the solvent. With the exception of this flocculent matter, much 

 greater quantities of resin can be dissolved in 100 cubic centimeters of ether, 

 ethyl and amyl alcohols than the amounts taken in the experiments described 

 above. 



Table I. — Per cent of substance dissolved from 10 grams of resin by 100 cubic 



centimeters of solvent. 



Solvent. 



Ethyl alcohol 

 Amyl alcohol 



Ether 



Ligroin 



Benzene 



Turpentine.. 



Percent. 



Temperature 



used to expel 



solvent. 





o 



95 



130 



97 



150-155 



75 



120 



32 



130 



50 



135-140 



40 



170-175 



The above figures are only approximate and represent averages, since 

 the solubilities of different pieces of the same grade vary slightly. The 

 terpenes, in some samples amounting to 10 per cent, will evidently be 

 expelled with the turpentine and lead to considerable error when this 

 solvent is used. 



Because of the lack of any simple method for separating resin and 

 linseed oil, no quantitative determinations of the solubility of the copal 

 in linseed oil were made. It appears to be a substance of about the same 

 solvent power as ligroin, turpentine, and benzene. 



As has been pointed out by Heupel, 39 all attempts to dissolve copals without 

 previous fusion have been unsatisfactory, at least commercially. The solubility 



"'Journ. Soc. Chem. hid. (1901), 20, 818. 



