406 EXPERIMENT STATION RECORD. 



entirely satisfactory in the hands of all the analysts, especially on 

 substances containing high percentages of phosphoric acid. For this 

 reason the convention directed that the method should be further 

 tested. 



The results of the tests of the official method of determining citrate- 

 soluble phosphoric acid were somewhat discordant, as well as those 

 with citric acid. The Wagner method gave very good results, consid- 

 ering the widely different methods of manipulation. 



The methods of examining slags were discussed at some length. In 

 this connection H. W. Wiley pointed out the need of an official method 

 for slag, which is likely to become an important fertilizer in Amer- 

 ican markets, and called attention to the importance of the degree of 

 fineness of the slag. He recommended the Wagner method for use 

 provisionally. 



H. A. Huston stated that investigations which he had made led him 

 to believe that all phosphoric acid in slag is in the tetra-basic form, and 

 if so it is all available. In his opinion the degree of fineness and the 

 total phosphoric acid make a safer basis of valuation than citrate solu- 

 bility, since the latter varies so greatly with slight variation in the 

 proportion of solvent to substance, temperature, etc. He recommended 

 that the complete analysis of slag be studied by the Association. 



The Association directed that the methods of analysis of slag be 

 studied by the reporter on phosphoric acid during the ensuing year 

 and that the Wagner method be printed in the proceedings. 



The results of the tests of methods of determining iron and alumina 

 do not admit of the drawing of any very definite conclusions. In all 

 the tests made with it the permanganate method was very satisfactory 

 for the determination of iron. The subject was referred to the reporter 

 for next year. 



Nitrogen. — The work of the Association during the year on methods 

 for nitrogen, as reported by J. P. Street, included (1) comparative tests 

 • by 11 analysts of the Ulsch- Street, 1 Schulze-Tiemann, 2 Kjeldahl, :i Gun- 

 ning,' Ulsch-Kjeldahl, 4 and Ulsch-Gunning 5 methods on nitrate of soda 

 containing 16.25 per cent of nitric nitrogen, a mixture of nitrate of 

 soda, cotton-seed meal, acid phosphate, and muriate of potash contain- 

 ing total nitrogen 3.71 per cent, nitric nitrogen 1.G3 per cent, and a 

 mixture of nitrate of soda and Lobos guano containing total nitrogen 

 4.56 per cent, nitric nitrogen 1.66 per cent; and (2) comparative tests 

 by 7 analysts of the solubility of the nitrogen of dried blood, cotton - 



1 U. S. Dept. Agr., Division of Chemistry Bui. 16. p. 21. 



2 Presenilis' Quantitative Analysis 1886, p. 473, using 7 to 10 gin. magnesium oxid. 

 3 U. S. Dept. Agr., Division of Chemistry Bui. 46, pp. 17, 18. 



'The so-called Fassbander method, substantially as originally described by von 

 Schenke in Chem. Ztg., 17 (1893), p. 977; U. S. Dept. Agr., Division of Chemistry Bui. 

 49, p. 16. 



5 Reducing as in the risch-Kjeldahl method, and then proceeding as in the Gunning 

 method 



