496 EXPERIMENT STATION RECOED. 



the lowest results, and the gravimetric method (official) gave the highest re- 

 sults when sulphuric acid was used as a solvent. Further work is t j be done 

 on these methods, with the same kind of slag. The committee appointed at the 

 last session to study the availability of the phosphoric acid in Thomas slag 

 phosphate also rendered a preliminary outline of methods, accompanied by 

 blueprints for field, pot, and cylinder experiments. 



The referee on nitrogen, C. L. Hare, reported the results of further study 

 of a method for organic nitrogen activity and on the Salle method for deter- 

 mining nitrogen in nitrates. Four out of 5 sets of results obtained with the 

 neutral permanganate method for organic nitrogen activity were in close agree- 

 ment, aud showed fairly uniform results in the hands of different analysts, 

 without reference to the material used. The results with the alkaline perman- 

 ganate method were not so uniform, except with treated feathers and mixed 

 fertilizers. The Salle method is deemed worthy of further consideration. 



H. B. McDonnell, as referee on potash, reported the results of cooperative 

 work, using kainit as the test material. The results obtained with the platinum 

 method were very satisfactory. The cobalti-nitrite method was not considered 

 reliable in its present form, and the results thus far obtained with the perchloric 

 acid method were low. Changes in the method of making the solution were also 

 tested, with practically the same results as in the official method. 



The associate referee on the availability of potash, E. E. Vanatta, reported on 

 several samples of fertilizers which were known to contain manure ashes, using 

 the official and J. L. Smith methods. The solubility of potash from such 

 sources seems to vary inversely with the degree of heat employed in the furnaces 

 used for burning the manure, and if the furnaces are too hot an insoluble sili- 

 cate o-f potash is in all probability produced. In the sample less than one-half 

 of the total potash was soluble when the official method was used. The re- 

 sults of some analyses of twigs and leaves from the peach tree are also in- 

 cluded. A proposed modification of the official method for availability of potash 

 was adopted, likewise a suggestion for making pot or plat experiments with 

 potash of known organic origin and with inorganic forms. 



G. S. Fraps, the referee on soils, reported on acidity methods of extracting 

 humus, and a comparison of the Rather with the official method. It was de- 

 cided that these various methods be studied further. 



As a result of cooperative work done with inorganic plant constituents the 

 referee, W. H. Mclntire, recommended that the associate referee, B. E. Curry, 

 be instructed to pursue studies with the Schreiber method for sulphur during 

 the coming year. Unsatisfactory results were obtained with the oxalate method 

 for iron and aluminum, and it was recommended that further study of this 

 method be discontinued. The molybdate method was adopted as official, and a 

 further study is to be made of its extension to the determination of calcium 

 as oxalate and magnesium as magnesium-ammonium phosphate. 



Following the report of the referee on insecticides, S. D. Averitt, the chromate 

 method for total lead oxid in lead arsenate was adopted as official. The pro- 

 visional methods for the analysis of lead arsenate were changed in accordance 

 with recommendation 7 of the referee in 1910 and adopted as official. 



L. F. Kebler, chairman of the committee on the testing of chemical reagents, 

 reported a decided impi'ovemeut in quality in the chemical reagents obtained 

 by the Bureau of Chemistry during recent years. Many chemists, however, are 

 still too willing to accept chemical reagents as delivered without questioning 

 their purity. 



The cocmittees on the unification of analytical methods, fats and oils, and 

 food standards were discharged. 



The referee on water, W. W. Skinner, reported the results of cooperative work, 

 and recommended tliat the phenol sulphonic acid method for nitrites and the 



