190 RICHMOND. 



in ether, benzene, and acetic acid. It did not fuse under 220° and con- 

 tained no substance which could be extracted with ammonium carbonate. 



Combustion of the dry, noncrystalline substance gave the following figures: 



I. 0.1817 gram substance gave 0.5150 gram C0 2 and 0.1634 gram H„0. 

 II. 0.2114 gram substance gave 0.5970 gram CO, and 0.1912 gram ELO. 



Calculated for C 3 oH 50 Oj. Found per cent. 

 Per cent. I. II. 



C=77.11 • 77.27 77.05 



H=10.04 9.98 10.02 



Molecular weight:=498. 

 The determination of the basicity was as follows: 



Milligrams of potash 

 per gram of resin. 

 N 

 1.0045 grams required 20.4 cc. —potash 113.9 



N ■ , 

 1.050/ grams required 21.0 cc. — potash 112.0 



whence 56.1 grams potash would neutralize 496 grams of acid. It is therefore 

 monobasic. 



That this last substance was manifestly impure was subsequently 

 shown by the fact that the precipitate obtained by neutralizing an 

 alcoholic solution of the dry substance with alcoholic potash was never 

 entirely soluble in water. All known potassium salts of resin acids 

 dissolve readily in water. The insoluble residue was also indifferent to 

 hot aqueous potash, which precludes lactone formation. 



The insoluble resin which was always left behind by tliis ■ means 

 possessed all the properties of the neutral resin which was obtained in 

 the same manner from the original, crude copal. It was entirely inert 

 to strong alkalis and scarcely soluble in the ordinary organic solvents, 

 but entirely soluble in an alcoholic solution of the resin acids. 



In view of the foregoing, no particular importance is placed upon the 

 results <5f the elementary analyses of the substance, or the close agree- 

 ment of the molecular weight with that of a monobasic acid of the 

 formula C. i: ,H 50 O 4 as determined from the potash value. 



NEUTRAL RESIN. 



A small portion of the resin which was precipitated from the alcoholic 

 solution of the original copal when the latter was neutralized with 

 alcoholic potash was also insoluble in water, slightly soluble in alcohol 

 and ether, but completely soluble in alcoholic solutions of the resin acids. 

 It is partially saponified by hot digestion with aqueous potash, leaving 

 a small proportion of substance practically insoluble in all solvents and 

 perfectly inert to alkalies. 



The saponification value of this neutral resin was found to agree 

 with the so-called ester number of the crude resin, and the amorphous 

 acid obtained from such saponification possessed properties analogous to 



