§ 145. RESIN-ACIDS, ETC.. 127 



RESINS, ANTHRAQUINONE-DERIVATIVES, BITtER PRINCIPLES, ETC. 



§ 145. Besm-aais and the moir, important meiluSds for their separa- 

 tion. 



With regard to tlie coniferous resin-acids, the observations made 

 in § 131 may be supplemented by the following; 



AUetic Cbcid^ occurs in lamellar crystals, softening at 129° and 

 melting at 144°, soluble in alcohol and ether, and forming salts 

 with most bases. Prolonged heating converts it into its anhy- 

 dride, which is soluble in a1)solate alcohol, and was formerly 

 known as pinic acid. The alcoholic solution of this substance 

 yields no crystals on evaporation ; it is gradually reconverted into 

 abietic acid by the continued actioii of 70 per cent, alcohol. 



Pimaric acid, from Pinus pinaster, forms granular crystalline 

 masses melting at 149°, difficultly- soluble in cold, biit easily in 

 boiling alcohol, and soluble in ether.- It resembles abietic acid in 

 most of its properties, but differs in possesising a bitter taste. 



For podoearpic acid see Oudemans j^ ^rrfemm, Stenhouse and 

 Groves ;* phyllic acid, Bougarel.* 



In isolating resin-acids one of the following methods will be 

 frequently found successful : 



a. Successive treatment with ipirit fif different strengths, finally 

 adding water and shaking with ether. It will be observed that 

 resin acids are, as a rulie, more easily soluble in dilute spirit than 

 resin-anhydrides, wax, etc. It was by this method that I suc- 

 ceeded in isolating wwKgwmic ffla'(i from a bark imported from 

 Madagascar.'' The residue obtained on evaporating the ethereal 

 extract was treated with 85 per cent, spirit, which left a wax 

 undissolved. The spirituous solution was evaporated, and the 



' Maly considered the acid formerly known as sylvic acid to be abietic ; 

 Duvernoy regards it as a modification of pimaric afeid. 



.2 Eer. d. d. diem. Ges. vi. 1122 ; Annal. d. Chem. und Pharm. clxx. 213 

 (Jonm. Chem. Soo. xxvii. 72). 



' Annal. d. Chem. und Pharm. oo. 311 (Jpum. Chem. Soo. 1878). 



* Union Pharm. xTiii. 262, 1877 (Journ. Chem. Soo. xxxii. 905). A sub- 

 stance similar to that described under the above name is often met with in the 

 analysis of herbaceous and leathery leaves. It is soluble in boiling alcohol, 

 and separates from such solution, after the wax, on evaporating and cooling. 

 It crystallizes in colourless scales, dissolves with difficulty in water and 

 glycerin, is .soluble in ether and chloroform, and also in warm potash, but pre- 

 cipitated by an excess of the latter. 



« Pharm. J|3 i. and Trans. [3], ix. 816 (1879). 



