17 



Eighteenth Convention, 1901, Bui. 67. 



Page 79, under "II. Quantity of material," first line, substitute 

 "0.35 to 0.45" for "0.8"; second line, substitute "tannin" for 

 "solid"; sixth line, substitute "0.35 to 0.45 " for "0.8," and "tan- 

 nin" for solids". 



Under "III. Moisture, (b) 1," substitute " 8 " for " 24 ";" (b) 2," 

 substitute "6" for "8"; strike out "to 110". 



Under "IV. Total solids," for "50 cc" read "100 cc". 



For paragraph "V. Soluble solids," substitute the following: 



Double-pleated filter paper (S. and S., No. 590, 15 cm) shall be used. To 2 grams of 

 kaolin add 75 cc of the tanning solution, stir, let stand fifteen minutes, and decant as much 

 as possible. Add 75 cc more of the solution, pour on filter, keep filter full, reject the first 

 150 cc of filtrate, evaporate the next 100 cc, and dry. Evaporation during filtration must 

 be guarded against. 



The optional method under this head, adopted in 1900, was stricken 

 out. 



Under "VI. Nontannins," for the first two lines substitute the 

 following : 



Prepare 20 grams of hide powder by digesting twenty-four hours with 500 cc of water 

 and adding 0.6 gram chrome alum in solution, this solution to be added as follows: One- 

 half at the beginning and the other half at least six hours before the end of the digestion. 

 Wash by squeezing through linen, continue the washing until the wash water does not give 

 a precipitate with barium chlorid. 



Insert the following provisional method: 



To 14 grams of dry chromed hide powder in a shaker glass add 200 cc of the tanning 

 solution; let stand two hours, stirring frequently; shake fifteen minutes; throw on funnel 

 with a cotton plug in the stem, let drain, tamp down the hide powder in the funnel, return 

 the filtrate until clear, and evaporate 100 cc. 



Throughout the method substitute 100 for 50 cc to allow for evapo- 

 ration. 



Nineteenth Convention, 1902, Bui. 73. 



Page 79, paragraph III, omit moisture determinations in extracts. 

 Change paragraph " (b)" under" III. Moisture" to read as follows: 



Evaporations shall take place under precisely the same conditions as to contact with 

 steam or with a metallic plate ; all dryings called for after evaporation shall be done by one 

 of the following methods under precisely the same conditions, so that the different residues 

 of each analysis may occupy the same shelves 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. 



Page 80, "V. Soluble solids," is to read as follows: 



Single-pleated filter paper (S. and S., No. 590, 15 cm) shall be used. To 2 grams kaolin 

 add 75 cc of the tanning solution, stir, let stand fifteen minutes, and decant as much as 

 possible (not on the filter), add 75 cc of the solution, stir, and pour on the filter. Keep 

 filter full, reject the first 150 cc of filtrate, evaporate, and dry next 100 cc. The portion 

 dried for determination shall be perfectly clear, and evaporation during filtration must be 

 guarded against. 



