S50 



ON VEfiETABLE ASTRINGENTS. 



nmriate of tin, the oxisu'.phate of iron, the acetate of lead, 

 alum, litne water, and sulphuric acid; and yet it is very 

 slightly affected by tartarized antimony, and nut in the least 

 by the carbonate of potash. Ave vve then to conclude, that 

 pure tarn, such as may be supposed to exist in Mr. Hat- 

 chett's preparation, has no affinity for the oxide of antimony 

 and the carbonate of potash ; and thai, when the ta . of the 

 gall-nut is precipitated by these reagents, i; depends upon 

 a primary action, which they exert upon some other con- 

 stituent ? or thai there, may be substances, which have some 

 specific differences, although, from their leading properties, 

 they may be ail of them strctly c^iti d to the generic 

 name of can ? The coincidence b ..ween Mr. Hatchett's tan 

 and rhatany, so far as the reage s are concerned, might 

 seem to favour the former opinion; yet the latter suppo- 

 sition implies nothing that is improbable, and is agreeable 

 to the analogy, which previh s in other vegetable pro- 

 ductions. 



With respect to any general conclusions, that I may draw 

 from my experiments on t! ese different vegetable astrin- 

 gents, I feel so well aware of the difficulty of obtaining un- 

 exceptionable results, and the uncertainty of the inferences 

 that ought to be deduced from them, t 1 at I shall not ven- 

 ture to consider the positions which I have advanced as as- 

 certained matters of fact, but rather as subjects for future 

 investigation. All that I can expect from this paper is, that 

 it will serve as an addition to the store of information which 

 is daily accumulating, and which may assist at some future 

 period in laying the foundation of a more matured theory, 

 than any which could be constructed at present, 



Liverpool, October 10, 1809. 



U. 



