and a ve^etalle Matter in some Vegetables. 103 



we were nevertheless at a lo?s how to account for its solu- 

 tion in water; this combination being in fact but veiy hllle 

 so of itself. 



Supposinii that the acids, which frequently exist in the 

 plants, and the tannin itselt when it is in excess, conid fa- 

 vour this solution, we thought il right to make some ex- 

 penments to verify this conjecture: after having saturated 

 therefore a solution of the tannin of gall-nuts with animal 

 glue dissolved in water, we treated tlie precipitate, when 

 well washed, with acetic acid on the one hand, and with 

 phosphoric acid on the other: these two acids produced, by 

 means of a slight heat, the complete solution of the iannate 

 of gclntiiir, or la/mated gelatine. 



"^ The following are tbe^prop-erties exhibited to ns by the 

 solution made with the acetic acid : 1. If we raise the tem- 

 perature to the boiling point, it becomes turbid and white 

 like milk, but precipitates nothing : -id. Neither the solution 

 of gelatine nor that of tannin prodiiccs any change in it: i 

 3d."ll precipitates iron black, and the acetate of lead yel- 

 low: 'Jth. Alcohol very much dephlegmated precipitates 

 the taniiale of gelatine ivom its acid solution in while Hakes, 

 which become brown when they unite. 



This last experiment shows, that when we treat with al- 

 cohol paits of vegetables which contain at the same time 

 acids soluble in this agent, and tannate of gelatine or ali)ii- 

 men, the (irst are taken up, and the other becomes insoluble 

 in the water, if there is nut in the vegetable matter some 

 other acid insoluble in alcohol. Thus, when we treat these 

 kinds of plants directly by water, we obtain, as we have said 

 above, much more of the combination of tannin and ani- 

 mal matter existing in the solution. 



It will be found from what precedes, that there is the most 

 remarkable analogy between the propenies of tannin and 

 animal o-elatine,and those of the natural combination which 

 we have discovered in several astringent vegetables : only 

 there is more tannin in the natural combination : the arti- 

 ficial contains more animal matter, and yields more am- 

 monia upon distillation. 



§ VI. Fiew as to the Existence of this Compoimd in many 

 Vegetables, and as to its Uies. 



Although we have only examined the combination in 

 quesiif)n in a small number of vegetables, we have reason 

 to think that it is very common among all of llicm. It is 

 that which sometimes makes the vegetable infusions turbid, 

 or is separated from them in the form of pellicles of various 

 G 4 ihicknessj 



