108 ON VARIOUS SPECIES OF CINCHONA. 



Spec. 1. Ye/hir hark. 



Infusion of 122 grammes, or near 4oz troy, of this bark, infused for 



* twenty-four hours in two litres [a little more than 2 wine 



quarts] of water at 12° [54*6° F.], imparted to it a yellow 



colour, and a very hitter and slightly astringent taste. 



Tested with va- This infusion occasioned a very copious flocculent precipi- 

 rious reagents. ... , .. r • • i 



° tate in a solution or isinglass. 



In a solution of sulphate of iron it produced a green co- 

 lour resembling that of bile, and some time after a precipi- 

 tate of the same colour fell down. 



The solution of antimoniated tartrite of potash was preci- 

 pitated by it of a yellowish white. 



The oxalate of ammonia threw down from it a precipitate, 

 which was oxalate of lime. 



Lastly it very evidently reddened tincture of litmus. 



This infusion, when completely precipitated by a solution 

 of isinglass, and filtered, was deprived of colour, and scarcely 

 at all astringent, but it retained its bitterness. In this state 

 mixed with a solution of sulphate of iron, it turned it green 

 as before, except that the colour inclined more to a yellow. 

 It still precipitated the solution of emetic tartar, with this 

 difference, that the precipitate was whiter. This cannot be 

 ascribed to an excess of the isinglass, for a solution of isinglass 

 occasions no change in that of emetic tartar. 



Another portion of the infusion, being completely precipi- 

 tated by emetic tartar and liltered, still rendered the solu- 

 tions of isinglass and sulphate of iron turbid, but much less 

 than before. The precipitate formed by the emetic tartar 

 was turned slightly green by the addition of a few drops of 

 sulphate of iron. 

 Principle that ^ W011 ^ appear from these experiments, that the principle 

 precipitates which precipitates emetic tartar, isinglass, and sulphate of 



nvmv d^tfrrent ir0n > is the Same ! anf * that ' I* tllG 1 ^ U ° r St ' lU ****** tbe pi '°" 

 ri-om that perty of precipitating isinglass and sulphate of iron, it is be- 



irli precipi. cnuse j t retains some portions of the combination of this 

 principle with antimony. This supposition however is not 

 reconcilable with the very copious precipitation of isinglass 

 by certain kinds of cinchona, that do not precipitate emetic 

 tartar. The principle >that precipitates isinglass therefore 



must 



Ifctcs gelatine. 



