ON VEGETABLE ASTRINGENTS. O4.7 



In my former paper I mentioned, that T hid performed Rhatany treat- 

 some experiments on the- extract of rhatany, which led me eA WJth wa?er 

 to conclude, that it consisted principally of tan. It readilv heat, 

 dissolves in water, and the solution i^ much promoted by an 

 increase of temperature; as the water cools, a part of the 

 rhatany separates, leaving" about t,-V df the weight of the fluid 

 in permanent solution. The fluid very slightly reddens lit- 

 mus, and alter some time shows, a tendency to mould. The 

 part that is deposited from the solution by cooling does not 

 appear to. be different from what is retained by the water, 

 except that it contains a small insoluble residuum, which I 

 am disposed to regard as an accidental impurity, and from 

 which it requires a number of successive infusions entirely 

 to separate the soluble part. That part which subsides 

 from the warm infusion is also less soluble than the entire 

 extract; but this I attribute rather to the effect of the ope- 

 ration, than to any original difference in its nature. Alco- an j Wll \^ a i co , 

 hoi takes up about T V of its weight of the extract, the so- hol » 

 lution is promoted by heat, it requires several successive 

 applications to remove all the soluble matter, and a portion 

 is left, upon which the alcohol has no longer any effect. 

 This part is readily dissolved by water, and forms a solu- Part - insolubIe 

 tion, which is of a bright red colour, which was rendered in alcohol, 

 slightly turbid by jelly and the oximuriate of tin, but was 

 very copiously precipitated by nitromuriate of gold and the 

 acetate of lead, the former producing a reddish brown, and 

 the latter a delicate pink precipitate. The results are very 

 similar to what has been related above respecting the action 

 of alcohol upon catechu, and indicates the presence of a 

 substance, which in its chemical characters bears an ana- 

 logy to mucus ; at the same time it must be remarked, that 

 the solutions of rhatany are free from any degree of visci- 

 dity. 



Rhatany acts very powerfully upon jelly, forming with it Action of re- 

 a light red precipitate, which generally separate s from the a S entsonu * 

 fluid. It appears, that the most perfect compound is pro- 

 duced by about equal parts of prepared isinglass and ex- 

 tract, but the substances do not unite in the same definitive 

 proportion, the nature of the compound being much in- 

 fluenced 



