§ 145. BESm-JClDS, ETC. 129 



course, tlie others remain in solution; or finally a mixture maybe 

 precipitated, in whicli, however, a separation may be effected by 

 treatment with solvents or by decomposition with carbonic acid, 

 etc. Hirschsohn met with a case of this description in his examina- 

 tion of galbamim.1 The resinous portion of the drug was digested 

 with soda, and to the solution chloride df barium was added tUl 

 no further precipitate was produced. From the dried barium 

 precipitate boiling alcohol dissolved a rather large amount, which 

 separated again on cooling, and contained only 1"07 per cent, of 

 baryta. This portion must have been carried down either 

 mechanically or in so loose a state of combination that boiling 

 spirit sufficed to effect a decomposition into acid- and base. The 

 alcoholic solution contained a second resin-acid, which was partly 

 precipitated on passing carbonic acid through the liquid, and 

 partly, in masses of fibrous crystals resembling asbestos, on the sub- 

 sequent addition of water. Boiling 95 per cent, alcohol extracted 

 it from the dried precipitate. The dilute alcoholic liquid, after 

 treatment -svitli carbonic acid, was acidulated with hydrochloric 

 acid, which threw down .a flocculent precipitate, soluble in 

 ammonia^ In addition to these three resins a fourth had escaped 

 precipitation with chloride of bariunu ■ It could be separated by 

 passing a current of carbonic acid through the alkaline solution. 



In fractionally precipitating with sUver or lead salts attention 

 should be directed to the percentage of the metal and the melting 

 point of the resin acid contained in the precipitates. These two 

 points are frequently of service in identifying acids. 



d. The mixed rosins may finally be separated by dissolving them 

 in spirit a,nd fractionally yrecipitiiiing with alcoholic solution of acetate 

 of lead. 



§ 146. Resins and Gumrredns of Commerce. — The examination 

 of commercial resins, and gum-resins, which generally consist of 

 ethereal oil and various resinous substances frequently accompanied 

 by mucilage, sugar, etc., was at my suggestion undertaken and 

 carried out by Hirschsohn. The following is an abstract of his 

 festilfs! -^ 



^ Pharm. Zeitschr. f. Eusslaiid, p. 225 et scj., 1875 (Pharm. Journ. and 

 Trans. [3], vii. 369 et seq.). . 



' Pharm. Zeitschr. f. Buasland, 225 et seq., 1875 ; 1 e« aeq., 1877. 'Beit- 

 rage zur Chem. der wichtigeren Harze, Gummiharze und Balsame,' Diss. 

 Xlorpat, 1877. Archiv d. Pharm. [8], x. 481 et aeq. ; xi. 54 et seq. ; xiii. 288 

 et seq. Pharm. Journ. and Trans, viii. 389 et aeq. 



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