£50 EXPERIMENTS Otf ASTRIKGENT VEGETABLES. 



acid. That acid cannot be fublimed, without being in part 

 deftroyed ; and, at the temperature of its fublimation, extrac- 

 tive matter is wholly converted into new produces. 

 Ether takes the Ether diflblves gallic acid; bat it has comparatively little 

 former m pre- ac ^i on U p 0n extractive matter. I have been able, in examining 



ferencc, but has . r , .„..,, 



little efteft as to lolutions of galls, to feparate a portion ot galhc acid by means 

 perfect fepara- f e ther. But, when the extractive matter is in large quanti- 

 ties, this method does not fucceed, as, in confequence of that 

 affinity which is connected with mats,*, the greateft part of 

 the acid continues to adhere to the extract. 

 Alumineattra&s Alumine has a ftrong attraction for extractive matter ; but 

 e*tra.a, but does comparatively a weak one for gallic acid f. When carbonate 



not feparate it ,. , . . J . .. & . '" . . 



perfectly from of alumine is boiled for fome time with a folution containing 

 gallic acid. extractive matter, the extractive matter is wholly taken up by 



the earth, with which it forms an infoluble compound ; but> 

 into this compound, fome of the gallic acid appears likewife 

 to enter ; and the portion remaining diflblved in the folution 

 is always combined with alumine. 

 This problem I have not, in any inftance, been able to feparate gallic acid 



fofv^f perfeaIy and extradive matter perfedly from each other; but I have 

 generally endeavoured to form fome judgment concerning their 

 relative proportions, by means of the action of the faltsof alu«* 

 Approximation, mine, and the oxygenated falts of iron. Muriate of alumine 

 precipitates much of the extractive matter from folutions, with- 

 out acling materially upon gallic acid ; and, after this precipi- 

 tation, fome idea may be formed concerning the quantity of 

 the gallic acid, by the colour it gives with the oxygenated ful- 

 phate of iron. In this procefs, however, great care mull be 

 taken not to add the folution of the ful phate of iron in excefs ; 

 for, in this cafe, the black precipitate formed with the gallic 

 acid will be rediflblved, and a clear olive-coloured fluid only 

 will be obtained. 

 The faline parts The faline matters in aftringent infufions, adhere fo ftrongly 

 of aftrmgent to t j ]e ve g e t a ble principles, that it is impoffible to afcertain their 



alio fcarcely to nature with any degree of accuracy, by means of common re- 

 be feparated. 



* See Berthollet, Recberches fur Us Lois de VAffinitL Mem. de 

 Vlnjiitut National. Tome III. p. 5. 



f See Fiedler, Journal de Chi?nit> par J. B. Van-mons, Tome I. 

 page 85. 



agents. 



