796 EXPERIMENT STATION RECORD. 



paring Neutral Ammonium Citrate Solution, by A. J. Patten and W. C. Marti, 

 was also presented. 



The report of C. L. Hare as referee on nitrogen showed in general uniform 

 and satisfactory results from the alkaline and neutral permanganate methods 

 for determining organic nitrogen activity, and the ferrous sulphate-zinc-soda 

 method for nitrogen in nitrates in raw materials and mixed fertilizers. The 

 permanganate methods were approved for official adoption in 1914. 



The referee on potash, H. B. McDonnell, reported work with the gravimetric 

 cobalti-nitrite method, the perchlorate method, and the platinic-chlorid method 

 with regard to the use of denatured alcohol for washing the potassium platinic 

 chlorid precipitate, and as to the advisability of adding 3 cc. of hydrochloric 

 acid to the aqueous solution of potash. Difficulty was experienced with the 

 perchlorate method owing to the solubility of the perchlorate precipitate in 

 strong alcohol and the insolubility of the impurities, including barium chlorid, 

 in alcohol. 



A paper on the perchlorate and gravimetric cobalti-nitrite method for the 

 determination of potash was read by T. D. Jarrell. E. E. Vanatta, the associate 

 referee on potash, reported preliminary cooperative work with M. F. Miller, of 

 Missouri, on the availability of the potash in feldspathic fertilizers. Barley was 

 grown in duplicate in stone pots containing 4 gal. of river sand and i gal. of 

 silt loam plus sodium nitrate, dried blood, acid phosphate, and a source of 

 potash, either a maximum or minimum addition of feldspathic fertilizer, potas- 

 sium sulphate, or potassimn chlorid. The yields of straw and grain were 

 greatest with potassium sulphate, but in only one case was the weight of grain 

 obtained with the feldspathic fertilizer less than that obtained with potassium 

 chlorid. Another study was made of the effect of cow manure in rendering 

 insoluble potash of soils available as plant food, as measured by its solubility 

 in boiling water. The sum of the potash extractions indicated that manure in 

 combination with soil decreases the amount of water-soluble potash, and a 

 moistened mixture seems to retain more of the potash than does a dry mixture. 



The referee on soils, G. S. Fraps, reported that cooperative work with the 

 Veitch method for acidity and laboratory work on methods for humus showed 

 variation much greater than desirable, but that the method is considered useful, 

 F. P. Veitch attributed the lack of uniformity in results to deviations from 

 the instructions. The humus work showed that it is possible to obtain a clear 

 filtrate from all soils examined according to O. C. Smith's procedure (noted on 

 page 718), but that some colloidal mineral material passes through into the 

 filtrate, which as previously noted (E. S. R., 25, p. 614) could be precipitated 

 with ammonium carbonate. Beam's method (E. S. R., 28, p. 19) gave satis- 

 factory results, but the soils tested required from 2 to 30 hours for washing and 

 the filter became clogged. 



W. H. Mclntire and J. I. Hardy pointed out that if the Rather method were 

 modified by filtering immediately after digesting 36 hours with 4 per cent am- 

 monium hydroxid, and then adding 2.5 gm. of ammonium carbonate to the 

 cylinder at the time of filtration on a Buchner filter with suction, a clear filtrate 

 is obtainable after 15 cc. of cloudy fluid has passed through the filter. The 

 average of 102 determinations with the same soil by the Rather method gave 

 an ash content of 0.35 per cent, varying from 0.24 to 0.52 per cent, while the 

 average of 81 determinations by the modification gave an ash content varying 

 from 0.11 to 0.24 per cent, and an average of O.IS per cent. The Rather method 

 on standing gave a precipitate but none was noted with the modified procedure. 



O. C. Smith, in a paper on humus determination, gave the results of a study 

 of 3 soils with the official, original Rather, and modified Rather method. The 

 association voted to discontinue the work on humus, to eliminate the official 



