#00 ON VEGETABLE ASTRINGENTS. 



which is afterwards taken up does not seem to be materially 

 different from what is first dissolved ; it only appears, that 

 in this, as in every other instance, the latter portions of so- 

 luble matter are retained more obstinately by the insoluble 

 part. The relative effect of jelly and the oximuriate of 

 tin were always, as far as I could judge, exactly in propor- 

 tion to the strength of the infusion, whether it formed in a 

 longer or shorter time ; in the infusions which were made 

 the most hastily, both the reagents produced a precipitate, 

 and however long the maceration had been continued, still 

 the effects seemed to be proportionate to each other. In- 

 deed the results which are obtained, when we make a num- 

 ber of successive infusions, are directly adverse to the com- 

 monly received opinion; for I found, as I have already 

 stated, that in the last infusions jelly was frequently capa- 

 ble of forming a precipitate after the oximuriate of tin, but 

 that the converse never took place. 

 Fatthef diffi- It may be farther observed, respecting the distinction.\be- 



"ilhinVSii 11 " twee " tan and extract > tnat tlie tw0 reagents, which are the 

 from extract, appropriate tests of each, jelly and the oximuriate of tin, 

 both of them act powerfully upon the opposite substance, 

 i. e. jelly upon extract, and the oximuriate of tin upon tan. 

 With respect to the latter, it is known that Proust, who 

 has exhibited so much sagacity on the subject of vegetable 

 infusions and their action upon the metallic oxides, origin- 

 ally introduced the muriate of tin as a reagent for tan, and 

 in his first experiments seems to have had no idea of its act- 

 ing upon any other substance*. And with respect to the 

 effect of jelly, whatever may be the body upon which it 

 exerts its primary action, we find, that, when it has ceased 

 to precipitate an infusion, what is then thrown down by the 

 oxide of tin is at least in very small proportion to what 

 would have been produced in the recent infusion. The 

 facts; which I have mentioned above, respecting the succes- 

 sive infusions and the formation of mould show an intimate 

 connexion between the two supposed substances, and in- 

 deed scarcely permit us to draw any line of distinction. 

 And the same idea will be still further countenanced by con- 



* Ann. de Chim. XXV, 225. 



siderinj 



