408 EXPERIMENT STATION RECORD. 



determination of iron and alumina by the acetate and the mol3ijdate 

 methods. From the results of the past two years and the referee's 

 experience with the modification of the volumetric method as proposed 

 by Runyan, he considered it not only rapid but capable of giving 

 highh' satisfactory results. But few results were reported on iron and 

 alumina, and those obtained were quite variable. With basic slag they 

 were not at all concordant, the manganese present interfering with the 

 determination. With ground phosphate and a mixture containing iron 

 and alumina the acetate method as modified by Carpenter gave quite 

 satisfactor}' results, but as the data on iron and alumina were meager, 

 no conclusions were drawn or recommendations made. The desira- 

 bility of the association taking some action on a method appplicable 

 to Thomas slag was urged. The referee considered some form of the 

 citric-acid method advisable, and the Wagner method as worthy of the 

 most favorable consideration. The use of the term "available phos- 

 phoric acid '' was deemed unwise. As phosphoric acid is in different 

 combinations in many materials, it was not \thought probable that a 

 single method would apply in all cases. 



H. A. Huston discussed the determination of iron and alumina. He 

 stated that results by present methods are worse than those obtained 

 ten years ago. He suggested taking up the study of new methods, 

 believing that the correct estimation of these elements is possible, 

 but that it is necessary for the association to proceed along new lines. 



No reconmiendations were adopted, but from the discussion it seemed 

 to be the sense of the association that the referee take up the study of 

 methods for basic slag. Digestion with citric acid was considered a 

 proper basis upon which to proceed. 



SOILS. 



The report on soils by the referee, M. E. Jafi'a, was read by the sec- 

 retary. The work of the past year related largel}" to methods of 

 determining available plant food, the citric-acid method and that of 

 fifth-normal hydrochloric acid for available potash and phosphoric acid 

 being studied. The results for potash were too meager to allow of a 

 definite recommendation. The tentative conclusion was reached that 

 any soil showing 0.02 per cent of KoO by either of the above methods 

 is not in pressing need of potash fertilizers. More work along this 

 line is urgentlj' desired, and attention was called to the fact that the 

 citric-acid method should not be discarded without further investigation. 

 Similar^, no definite conclusions were reached with phosphoric acid. 

 The work along the line of humus and humus nitrogen was for the pur- 

 pose of determining the relation, if anj^, which exists between the nitro- 

 gen extracted by ammonia and that contained in the NaOH and KOH 

 leachings. The comparison of humus nitrogen extracted b}' NH3 and 

 NaOH solutions was not ver}" satisfactoiy. There was an agreement 

 between some of the results for the nitrogen by NaOH, but those by 



