S., No. 590, 15 cm.), returning the first 25 c. c. and adding 2 grams of kaolin if 

 necessary. Evaporate 100 c. c. of the clear filtrate. The weight of this residue 

 must be corrected for the dilution caused by the water contained in the pressed 

 hide powder. The shaking must be done in some form of mechanical shaker. 

 The simple machine used by druggists, and known as the milk shake, is 

 recommended. 



PROVISIONAL METHOD. 



To 14 grams of dry chromed hide powder in a shaker glass add 200 c. c. of 

 the tanning solution, let stand two hours, stirring frequently, shake fifteen min- 

 utes, throw on funnel with a cotton plug in the stem, and let drain. Collect 

 the filtrate and filter through a folded filter (S. and S. No. 590, 15 cm.), return- 

 ing the first 25 c. c. and adding 2 grams of kaolin if necessary. Evaporate 

 100 c. c. of the clear filtrate. 



VI. TANNINS. 



The amount of these is shown by the difference between the soluble solids 

 and the corrected non-tannins. 



VII. TESTING NON-TANNIN FILTRATE. 



Test a small portion of the clear non-tannin filtrate with a few drops of a 1 

 per cent solution of Nelson's gelatin. A cloudiness indicates the presence of 

 tannin, in which case repeat the process described under V, using 25 instead of 

 20 grams of hide powder. 



VIII. PROVISIONAL METHOD FOR THE DETERMINATION OF TOTAL ACIDITY 



IN LIQUORS. 



Place 100 c. c. of the liquor in a 500 c. c. flask and make up to the mark with 

 water. To 100 c. c. of diluted liquor in a flask with tube condenser add 2 

 grams of chemically pure animal charcoal. Heat to boiling temperature with- 

 frequent shaking, cool, filter, and titrate an aliquot portion with decinormal 

 alkali. 



IX. METHOD OF DRYING. 



Evaporations shall take place under precisely the same conditions as to con- 

 tact with steam or with a metallic plate. All dryings shall be made in flat- 

 bottom dishes of at least 6 cm. diameter. All dryings called for after evaporation 

 shall be done by one of the following methods under precisely the same condi- 

 tions, so that the different residues of each analysis may occupy the same shel VPS 

 in the drying oven. 



1. For eight hours at the temperature of boiling water in steam oven. 



2. For six hours at 100 C, in air bath. 



3. For five hours at 100 C, in vacuo. 



H. W. WILEY, 



Chief of litircftit and tfnrclnry A. (). A . C. 

 Anproved : 



JAMKS WILSON, 



Secret <tri/ of Agriculture, 



\V\mn.VGTON, P. C., 



O 



