CONVENTION OF OFFICIAL AGRICULTURAL CHEMISTS. 407 



seed meal, dried fish, tankage, hoof meal, raw leather, wool waste, bone 

 sa wings, and steamed and raw bone in pepsin solution 1 and in acid and 

 alkaline potassium permanganate solution. 2 



The results by the Ulsch-Street method for nitrates were good, agree- 

 ing very closely with those obtained with the Schulze-Tiemann method, 

 but the Kjeldahl method for nitrates did not give entirely satisfactory 

 results. The Ulsch-Kjeldahl and Ulsch-Gunning method seemed to be 

 fully as satisfactory as the Kjeldahl method on the mixed samples, but 

 it is believed that they may be further improved. 



E.E.Ewell reported that the Schulze-Tiemann method had proved very 

 satisfactory in his experience, and he described some improved pieces 

 of apparatus for use in this method. A. L. Winton stated that he had 

 found the Ulsch-Gunning method satisfactory with fertilizers having a 

 low percentage of nitrates, but that it was necessary to use a larger 

 amount — 3 gm. as a rule — of iron than is recommended in the present 

 method. 



The Ulsch-Street method for nitrates was made an official method, and 

 the reporter was instructed to study further the Ulsch-Kjeldahl and 

 Ulsch-Gunning methods for total nitrogen in presence of nitrates. 



The pepsin and permanganate methods for determining availability 

 of nitrogen gave discordant results in the hands of different analysts, 

 this being especially true with the permanganate methods. 



J. B. Lindsey and A. L. Winton discussed briefly the methods of 

 determining available nitrogen in fertilizers, and advocated digestion in 

 pepsin solution as preferable to the permanganate method. 



The reporter was instructed to make a more thorough study of these 

 methods during the coming year, including, in addition, tests of a 3 

 percent neutral permanganate solution. The method proposed for the 

 latter purpose is as follows : Digest 1 gm. of substance in 100 cc. of 

 neutral 3 per cent potassium permanganate in a steam bath for 30 min- 

 utes, shaking occasionally; add 700 cc. of cold water, filter, wash 3 or 

 1 times, using in the aggregate from 125 to 150 cc. of water; determine 

 nitrogen in the residue by the Kjeldahl method. 



Potash, — The report of A. L. Winton on methods of determining- 

 potash was devoted to the results of comparative tests by 7 analysts of 

 (1) the Stassfurt method, 3 (2) the optional method, acidulating with 

 hydrochloric acid before precipitating sulphuric acid; (3) the Lindo- 

 Gladding method, without removal of lime, as well as (4) an inquiry 

 into the possibility of reducing the amount of platinum chlorid used. 



"The materials [used] . . . consisted of pure potassium chlorid, pure potassium 

 sulphate, aud mixtures representing the imparities in each of the four manure salts 

 commonly sold iu the United States. The 'impurities' were distributed in vials in 



1 Connecticut State Sta. Rpt. 1893, p. 219. 



2 U. S. Dept. Agr., Division of Chemistry Bui. 49, p. 21. 



3 This is essentially a modification of the "short method" of Fresenius. See 

 Ztschr. angew. Cheui., 1895, p. 510. 



