BXPliRlMKNTS ON ASTRINGENT VEGETABLES. 37 



An ounce of Malaga fumach, produced 156 grains of folu- 

 ble matter, of which 79 appeared to be tannin. 



The infufion of Myrobalans * from the Eali Indies, differed Of Myrobalans. 

 from the other aftringent infufions chiefly by this ciicumflance, 

 thafit effervefced with the carbonated alkalis j and it gave with 

 them a denfe precipitate, that was ahiioft immediately redif- 

 folved. After the tannin had been precipitated from it by ge- 

 latine, it flrongly reddened litmus-paper, and gave a bright 

 fclack with the folutions of iron. I expeded to be able to pro- 

 cure gallic acid, by diftillation from the Myrobalans ; but in 

 this I was miftaken ; they furniflied only a pale yellow fluid, 

 which gave merely a flight olive tinge to fohition of fulphate 

 of iron. 



Skin was fpeedily tanned in the infufion of the Myrobalans ; 

 and the appearance of the leather was fimilar to the appear- 

 ance of that from galls. 



The flrongeft infufions of the teas are very fimilar, in their 

 agencies upon chemical tefls, to the infufions of catechu. 



An ounce of Soucjiong tea, produced 4S grains of tannin. 



The fame quantity of green tea, gave 41 grains. 



Dr. Maton has obferved, that very little tannin is found in 

 cinchona, or in the other barks fuppofed to be pofiefled of 

 febrifuge properties. My experiments tend to confirm the ob- 

 fervation. None of the infufions of the ftrongly bitter vegetable 

 fubftances that I have examined, give any precipitate to gelar 

 tine. And the infufions of quaflja, of gentian, of hops, and 

 of chamomile, are fcarcely affeded by muriate of tin ; fo that 

 they likewife contain very little extractive matter. 



In all fubflances poflelled of the afiringent tafte, there is 

 great reafon to fufpeft the prefence of tannin ; it even exifts in 

 fubftances which contain fugar and vegetable acids. I have 

 found it in abundance in the juice of floes; and my friend Mr, 

 Poole, of Stowey, has detecled it in port wine. 



V. GENERAL O BSEK V ATXONS. 



Mr. Proufi: has fuppofed, in his paper upon tannin and its P'obability that 

 Species,! that there exift different fpecies of the tanning prin-^l^^^pedestf"' 

 ciple, pofleffed of different properties, and difterent powers tanning matter, 



* The Myrobalans ufed in thefe experiments are the fruit of the 

 Jerminalia Chebula. Retz. Obs Botan. Fafc. V. p. 31. 

 t Annales de Chimie, Tome XLI. p. 332. 



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