128 RESINS, BITTER PRINCIPLES, ETC. 



mass treated with 50 per cent, spirit, in which a little brown 

 resin was found to be insoluble. To the alcoholic solution ether was 

 added, and then sufficient water to cause separation. On well 

 shaking the ether dissolved the whole of the mongumic acid, the 

 addition of a few drops of acetic or hydrochloric acid facilitating 

 solution. The mongumic acid was then obtained by evaporating 

 the ethereal liquid. 



b. Treatment of the mixed resins with a solution of soda or potash in 

 dilute spirit, and recovery of the resin by the addition of acetic or 

 hydrochloric acid and filtering, or, if very finely suspended, 

 shaking with ether. I adopted this method in separating a resin- 

 acid from paeony-seed. 1 The mixed resins were treated with 

 boiling 85 per cent, spirit, and the liquid kept at for some time, 

 to allow of the separation of a little resin anhydride that had 

 been carried into solution. To the filtrate water was added till 

 the spirit was reduced to a strength of 50 per cent., by which the 

 resin was precipitated. The mass was then dissolved in a solu- 

 tion of soda in 50 per cent, spirit, again precipitated by the 

 addition of acid, and finally decolourized in alcoholic solution by 

 animal charcoal. In adopting this method the requisite strength 

 of the spirit must be ascertained by preliminary experiments. 



c. Treatment of the mixed resins with aqueous soda or potash. 

 Any resin dissolved by the alkaline liquid may be generally re- 

 covered by acidification with acetic or hydrochloric acid. (Com- 

 pare also 45). 2 It is, moreover, not unfrequently possible to 

 obtain sparingly soluble combinations of the resin with silver, lead, 

 barium, calcium, etc., by adding salts of those metals to the solu- 

 tion of resinate of soda. This method is sometimes successful in 

 cases of mixtures of several resin-acids or of a resin-acid with other 

 resinous substances soluble in solution of soda. The resins present 

 may be separated by fractional precipitation ; or it may happen 

 that only one is precipitated by the salt used, in which case, of 



1 Archiv d. Pharm. [3], ix. 426, 1879 (Journ. Chem. Soc. xxxvi. 1043). 



2 dirt/sin, discovered by Piccard in the buds of the poplar (Ber. d. d. chem. 

 Ges. vi. 884, 1873; Journ. Chem. Soc. xxvi. 1236) might be isolated by this 

 method. It is precipitated yellow by acids, is somewhat sparingly soluble in 

 ether and alcohol, and almost insoluble in petroleum, bisulphide of carbon, 

 chloroform, and benzene. The latter, when warm, removes the so-called 

 tectochrysin. An alcoholic solution of chrysin is coloured violet by ferric- 

 chloride, and gives with neutral acetate of lead a yellow precipitate, soluble in 

 excess and in glacial acetic acid. 



