186 RICHMOND. 



In the case of Manila copal, which is only partially soluble in ether, 

 a much better scheme of analysis was found to be as follows : 



The crude, mined resin is dissolved in strong alcohol in which it is completely 

 soluble except for the varying proportion of dirt and other foreign matter which 

 may be present. The filtered solution is then made alkaline by the addition of 

 alcoholic potash in slight excess, which precipitates a white, semigranular mass 

 which adheres to the bottom of the flask and from which the clear, supernatent 

 alcohol may readily be decanted. The alcohol is then removed by distillation 

 and the residue taken up with water and extracted with ether. The etherial 

 extract is dried over solid potash and evaporated to constant weight. The residue 

 is a pale lemon colored, mobile oil of terpene-like odor. 



The aqueous portion is warmed to expel the dissolved ether and acidified with 

 dilute hydrochloric acid in slight excess, the precipitated resin washed free from 

 potassium chloride and dried under reduced pressure over sulphuric acid to 

 constant weight. 



The semigranular resinous mass which is precipitated from the alcoholic 

 solution of the original resin upon neutralization with alcoholic potash is treated 

 with hot water, in which it is soluble, except for a small proportion of gelatinous 

 residue which can not be completely separated 'by filtration. Extraction with 

 ether in which the insoluble portion is partially soluble effects a complete me- 

 chanical separation from the soluble alkaline resinate. The ether extract con- 

 taining the partly dissolved, unsaponified portion is evaporated to dryness at 

 100°, leaving a grayish, brittle, amorphous resin. 



The aqueous portion of the precipitate, insoluble in alcohol, is in turn washed 

 to expel dissolved ether and the resin precipitated with dilute hydrochloric acid. 

 The washed, amorphous resin is dried to constant weight. 



One hundred parts of the crude resin treated in this manner gave the 

 following : 



Parts. 



Insoluble in absolute alcohol 0.5 



Soluble in alcoholic potash 40.0 



Insoluble in alcoholic potash 41.5 



Neutral oil soluble in alcohol and volatile with steam 6.0 

 Neutral resin partially soluble in alcohol and nonvolatile 



with steam 10.0 



Water, etc., undetermined 2.0 



100.5 



These results agree very closely with those reported by Tsehirch for a 

 sample of spirit soluble Manila copal, and confirm his general conclusions : 



(1) That Manila copal consists mainly of amorphous, free resin acids; 



(2) it contains a neutral resin, indifferent to alkalies; and (3) a volatile 

 oil. 



However, it should be noted that Tschirch's so-called hard variety 

 contained no acid extractable with ammonium carbonate and was only 

 partially soluble in alcohol; whereas the hard mineral resin examined in 

 this laboratory is soluble in alcohol and does contain a small proportion of 

 an acid soluble in ammonium carbonate. 



