26 



" As however, I have made several experiments 

 to ascertain the proper mode of proceeding, and 

 acquired some experience in the matter, I willingly 

 communicate it, and devote the remainder of this 

 paper to hints which I hope may be of service to 

 the tanner in going through the test on his own 

 account. 



" As the object is to constitute a comparison be- 

 tween two or more astringents, and decide quickly 

 jyn their respective merits, whilst the articles are 

 yet at market, a few pieces should be selected from 

 each lot, so as fairly to represent every parcel. 

 The whole of each sample should be separately 

 ground to powder in a small coffee or pepper-mill, 

 and passed successively through the same sieve, to 

 place each in similar circumstances. From these 

 average samples, the operator may take equal 

 weights, and obtain complete infusions of each, by 

 agitating them with successive portions of warm 

 water till all the soluble matter is extracted. 



Though boiling water will hasten the operation, 

 it certainly tends to decompose the astringent 

 liquor afterward, and induces it to deposit a portion 

 of insoluble matter which may interfere with cor- 

 rect results. Water at blood heat (98° Fahr.) 

 may be safely applied ; bottles to infuse and shake 

 the powders in, and a piece of muslin to strain 

 through, serve these purposes completely. Care 

 must, of course, be taken to preserve and return 

 any powdered bark which may remain in the 

 strainer, with the next quantity of warm water. 

 Successive additions in this manner are exceedingly 

 more powerful solvents than the whole quantity 



