ON VEGETABLE EXTRACT. 75 



XII. 



On Extract and the Saponaceous Principle', by Mr. 

 ScHrader, of Berlin,*- 



jf\.FTER quoting- the works of Rose, Hermbstaedt, Writers oaths 

 Trommsdorf, Fourcroy, and Vauqiieliuf, all of whom SU JCC ' 

 have examined these two matters, the author adds: 



If oxidation be the principal characteristic of extract, Peruvian bark 

 cinchona is the substance that should be preferred for obtaining it. 

 obtaining* it. Accordingly I exhausted some cinchona 

 {china fusca et officinalis) by alcohol, till the menstruum Treated with 

 was do longer coloured. The tinctuVe obtained had no alc °ho!, 

 action on solution of gelatine, but it reddened litmus 

 paper, and precipitated sulphate of iron green. 



Having subjected the tincture to distillation, water was 

 poured on the residuum ; when a sediment formed, which 

 was separated. 



The cinchona exhausted by alcohol was treated with cold c^ J water, 

 water. Litmus paper and sulphate of iron were not per- 

 ceptibly affected by the impression; but it precipitated 

 gelatine. This - aqueous solution was evaporated and re- 

 dissolved several times, and each time the precipitate that 

 formed was collected. Lastly, this extract was purified 

 from cinchonate of lime by alcohol, and mixed with the 

 alcoholic tincture. 



The cinchona, that had been treated successively by and boiling 

 alcohol and cold water, was boiled in water. The brown 

 decoction was likewise evaporated and redissolved several 

 times, taking care to separate the flocculent matter that 

 subsided. This sediment afforded a brown powder, having 

 distinctly the smell of extract of cinchona; whi$h was 

 little soluble in boiling water, or in alcohol, but formed a 



* Ann. de Chim. vol. LXXIJ, p. 290. Abridged fiom Gehlen's 

 Journal by Mr. Vogel. 



■f See also a paper on Vegetable astringents, by Dr. Bostock, 

 Journal, vol. XXIV, p 204, 241, in which the existence of extract 

 as a separate principle is rendered very questionable. Dr. Henry 

 however remarks, Elements of Chemistry, vol. II, p. 18], that Dr. 

 Bostock did not examine the extract from saffron. C. 



red, 



