16 



Twenty-second Convention, 1905, Bui. 99, Cir. 26. 



The provisional nitric-acid method for sulphur in plants was 

 dropped. 



The peroxid method was adopted as provisional for the determi- 

 nation of sulphur in plants: 



PROVISIONAL PEROXID METHOD FOR DETERMINATION OF SULPHUR IN PLANTS. 



Weigh out 15 grams of sodium peroxid (free from sulphates) and introduce about three- 

 fourths of it at once into a 100 cc nickel crucible ; add a little water and boil over a sulphur- 

 free flame until excess of water is completely driven off. Allow to cool until pasty and 

 stir 2 grams of material into it as quickly as possible; heat cautiously until danger of foam- 

 ing has passed, adding the remainder of the peroxid in small portions from time to time 

 to complete the oxidation. After fusion is complete, allow crucible to cool; dissolve con- 

 tents in water, transfer to a beaker, and add a slight excess of hydrochloric acid. Heat 

 to boiling, filter if not perfectly clear; dilute to about 400 cc and add 10 cc of a 10 per cent 

 solution of barium chlorid. Let stand over night, filter, and weigh the barium sulphate 

 in the usual manner. Make blank test with the reagents. 



VIII. METHODS FOB THE ANALYSIS OF TANNING MATERIALS. 



i 



Seventeenth Convention, 1900, Bui. 62. 



Page 79, "III. Moisture, (b), 2," for "103" read "110". 

 Page 79, " IV. Total solids," first line, for " 100 cc " read " 50 cc". 



Page 80, "V. Soluble solids," first line, for " double-folded filter" 

 read " double-pleated filter"; second line, for " 100 cc" read "50 cc"; 

 fourth line, for "kaolin" read " barytes ". After the paragraph insert 

 the following optional method : 



Optional method. 

 \ 



(a) To 100 cc of the solution add 10 cc of a solution of lead acetate (4 grams per liter), 

 adding the reagent drop by drop from a burette arid stirring meanwhile. Add 10 cc of a 

 solution of acetic acid (36 grams glacial acid per liter), stirring. Throw on double-pleated 

 filter, reject until clear, and evaporate and dry 50 cc 



(6) On another portion of 100 cc repeat the foregoing, except that 20 cc of lead acetate 

 solution shall be used. 



Residue from (a) shall be multiplied by 1.2, and from (b) by 1.3, to bring back to the 

 original 100 cc. Add to the corrected weight of the residue from (a) the difference between 

 (a) and (6) and calculate the lound residue to soluble solids Thjs corrects for dilution 

 and removal by lead. 



Page 80, "VI. Non-tannins," for lines 6-9 substitute the following: 



Weigh the remaining three-quarters, which must contain between 12 and 13 grams of 

 dry hide, add to '200 cc of the solution, and shake 10 minutes. Throw on funnel with 

 cotton plug in stem, return until clear, evaporate 50 cc, and dry. 



Page 80, "VIII. Testing hide powder, (a)," fourth line, for "100 

 cc" read "50cc"and for "10 nag" read" 5 nig"; "(&)," second line, 

 for "100 cc" read "50 cc". 



Add paragraph (c), as follows: 



(c) Any analysis made with a powder which does not fulfill the conditions of the preced- 

 ing paragraphs shall not be reported as by this method. 



