CONVENTION OF OFFICIAL AGRICULTURAL CHEMISTS. 407 

 FERTILIZERS. 



Nitrogen. — Tii the absence of the referee, W. R. Perkins, the i-eport 

 was read by E. B. Ferris. The work during- the past year was a 

 continuation of trials of the neutral permanganate (Street) and alka- 

 line permanganate (Jones) methods for determining available organic 

 nitrogen. In su])mitting the results obtained and the conmicnts of 

 the ditferent anal^-sts, the referee suggested that the time of digest- 

 ing, in determining total nitrogen, receive the attention of the asso- 

 ciation, as samples with a high nitrogen content do not give uniform 

 resul.ts after digesting* three hours. While the results by the neutral 

 permanganate method did not agree perfectly, the method was 

 regarded as of value in distinguishing between the different grades of 

 nitrogenous material as determined by vegetative tests. The referee 

 submitted several minor modifications, and recommended that the 

 method with these modifications be adopted provisionally, and that the 

 alkaline permanganate method be further tested. These recommenda- 

 tions were adopted by the association. 



Potash. — In the absence of the referee, C. L. Hare, the report was 

 read by B. B. Ross. The accuracy of the Lindo-Gladding method in 

 case of mixtures of acid phosphate and potash salts was investigated, 

 and also the use of ammonium chlorid as a possible aid in securing 

 complete solution of the potash, and a method devised by the referee, 

 employing milk of lime for precipitating potash from neutral solution. 

 A mixture of potassium chlorid and acid phosphate in the proportion 

 of 5 to 95, the theoretical amount of potash present being 3.35 per 

 cent, gave the following average results: Lindo-Gladding method, 3.12 

 per cent; the Lindo-Gladding method with ammonium chlorid. 3.19 

 per cent, and the milk of lime method, 3.15 per cent. While the 

 addition of ammoniimi chlorid gave higher results, these do not war- 

 rant the conclusion that this addition is an advantage. The large 

 amount of ammonia salts left after expelling the sidphuric acid may 

 cause loss from sputtering. Special attention was called to the results 

 obtained by the milk of lime method, the details of manipulation of 

 which were given, and the results in comparison with the Lindo-Glad- 

 ding method with a large nimiber of fertilizers containing organic 

 materials were shown. From the results of his investigations the ref- 

 eree suggested that the cause of the low results obtained by the official 

 method be further investigated, and that the milk of lime method be 

 submitted for trial during the coming year. These suggestions were 

 adopted. 



Phosphoric add. — In the absence of the referee, H. K. Miller, the 

 report was read by K. G. Runyan. The work on phosphoric acid con- 

 sisted in testing the determination of total phosphoric acid l)v the offi- 

 cial gravimetric method in comparison with the volumetric, and the 



