ON VE5ETABLE ASTRINGENTS. 20£? 



which ave employed in the analysis of galls, the firft being- 

 supposed to indicate the presence of the extractive principle, 

 the latter of the tan. The accuracy of this deduction I shall 

 hereafter examine, but admitting it for the present, I may 

 observe, in the first place, that an infusion of galls, which, 

 when recent, was copiously precipitated both by the muriate 

 of tin and by jelly, after it has undergone the process of 

 moulding, will be found no longer capable of being acted 

 upon by the first of these reagents, while the effect of the 

 second is very considerably diminished. Secondly, if suc- 

 cessive infusions be formed from the same galls, it is only 

 the first infusions, which are capable of moulding, and it is 

 these only which form a precipitate with the muriate of tin 

 and with jelly. Hence we may conclude, that the capacity 

 of moulding is intimately connected both with that part of 

 the galls which precipitates the muriate of tin, and also, 

 though perhaps, in a less degree, with the tan*. 



" In 



* 1 think it probable, that fey proper management, an infusion of galls Infusion of* 



might, by the operation of moulding, be deprived of all its tan, as well as gal's might 



of what has been culled the extract. I kept a quantity t/f the infusion P e . r a P s r ' >c !, t . e " 



, - privedof all itc 



exposed to the atmosphere for several weeks, and from time to time de- tan by raou ^. 



stroyed the covering of mould as it was produced. Long after the in- ing, 

 fusion ceased to be affected by the oximuriate of tin, the mould conti- 

 nued to be formed, and the power of affecting jelly obviously decreased, 

 until at length it did no more than produce a degree of turbidness with- 

 out throwing down a precipitate. At this period, however, the whole of 

 the fluid became so filled with the remains of the mould, and with the 

 sediment which was deposited at the same time, that the experiment 

 could not be pursued. Tr«mmsdorf, as I have noticed above, attributes 

 the f0rrr.2j.ion of the mould to mucus, and even employs this operation to 

 remove this substance, in order to obtain tan in a state of purity. I 

 could not repeat his proces?, because I was not in possession of any per- 

 fectly pure alcohol, which is essential to its success. I would be under- 

 stood therefore as speaking with much diffidence, when I observe, that t 

 doubt whether it will be found practicable. It gees Upon the assumption 

 of the two data, that the extract alone is rendered insoluble by the appli- 

 cation of heat and by exposure to the atmosphere, and that the mucus 

 atone is separated by the moulding, both which, according to my experi- vf ou i {][{„£ no * 

 ments, are incorrect. Mt. Deyeux himself has observed (a), that the re- confined to 

 sldue obtained by evaporating the^tmcture of galls, when dissolved in mucilage. 



(a) Ann. Chem. XVII, 10. 



Voi,. XXIV— Nov, 1809. P water. 



