18 



Under "VI. Nontannins," use 2 grams kaolin when filtering. 



Omit paragraph " VIII. Testing hide powder/'and"(b)" under "IX. 

 Testing nontannin filtrate." 



The following provisional method for the determination of total 

 acidity in liquors was adopted : 



DETERMINATION OF TOTAL ACIDITY IN LIQUORS. 



Place 100 cc of the liquor in a 500-cc flask and make up to the mark with water. To 100 

 cc 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. 



Twenty-first Convention, 1904, Bui. 80, Cir. 20. 



Page 79, under "II. Quantity of material/' change the last sentence 

 to read as follows: "In the case of extracts, weigh in a weighing 

 bottle fitted with a ground glass stopper such quantity," etc. 



Page 80, the following method for the analysis of barks, woods, etc., 

 was adopted as provisional : 



PROVISIONAL METHOD FOR BARKS, WOODS, LEAVES, ETC. 



I. Moisture determination. 



Immediately upon receipt of sample grind or crush as finely as possible 25 grams, and 

 dry for 12 hours at 100 C., reweigh, and calculate difference as H 2 O. 



II. Preparation of sample for extraction. 



Barks, woods, leaves, and other tanning materials, such as nut galls, myrobalans, etc., 

 should be dried sufficiently to facilitate grinding and then ground to such a degree of fineness 

 that the sample will pass through a sieve of 14 meshes to the inch (linear). 



In case of a coarser residue being left after sieving the portion ground, it should be 

 reground until the entire quantity passes through the sieve. A style of grinder should be 

 used that will make a granular preparation of the desired size, not finer. An excess of dust 

 and very fine particles must be guarded against in order that a rapid and complete extrac- 

 tion be obtained. 



III. Quantity of sample to be used for extraction. 



Such a quantity of the material to be analyzed should be taken as will yield a sufficient 

 volume of liquor having a specific gravity of 1.0025 at 15 C. Should the gravity of the 

 liquor prove greater than the above, dilute to the desired point with water about 80 C. 

 If, however, it should prove impracticable to obtain from spent material the necessary 

 volume of liquor of the gravity specified, the gravity should be taken and the quantity of 

 hide powder used to precipitate the tannin, reduced in proportion. 



IV. Extraction of sample. 



The extraction may be carried out in any form of extractor that will give complete extrac- 

 tion, with a yield of not more than 1 liter of liquor. A temperature of 100 C. should be 

 maintained throughout the entire operation, except in the case of sumac and starch -bearing 

 materials, when a maximum of 80 C. will be found better, and extraction continued until 

 resulting liquor shows no precipitation with gelatin solution, as by the method for testing 

 nontannins. Should the volume of liquor prove insufficient, dilution should be made imme- 

 diately with water at 80 C. to as near the mark as possible. 



In case of pulverized or finely ground material, such as sumac, powdered nut galls, etc., 

 the extraction will be materially assisted by thoroughly mixing the sample with glass sand 

 free from iron and matter precipitable or soluble in hot tannin solution. 



