CONVENTION OF OFFICIAL AGRICULTURAL CHEMISTS. 505 



C. H. Jones called attention to a study which had been made at the 

 Vermont Station of the alkaline-permanganate method for determining 

 the availability of organic nitrogen in fertilizers. The main results of 

 this work are summarized as follows: l 



"(1) The alkaline-permaugauate method (16 gm. potassium permanganate, 150 

 gm. sodium hydrate to 1,000 cc. ; 100 cc. used in 600 cc. flask; digestion for an hour 

 helow boiling, followed by an hours distillation^ has shown in our hands broad 

 distinctions between materials of animal origin of high and low nitrogen availa- 

 bility, provided amounts of substance equivalent to 0.045 gm. of nitrogen are used. 



"(2) It is simpler and far more rapid than the pepsin-digestion method, and 

 should prove particularly useful in eliminating quickly from a long list of fertilizers 

 a large share of goods which would surely show high availabilities by the longer 

 and more tedious processes. Its failure to show a sufficient availability with 

 unacidified vegetable ammoniates may be overcome by the use of the pepsin method 

 in doubtful cases. 



"(3) Materials falling below 50 per cent nitrogen availability by this method are 

 open to suspicion; those falling below 10 per cent are surely of little value for the 

 production of crops. All such, however, should be likewise tested with pepsin, and, 

 if opportunity admits, may be subjected to vegetation tests. 



" (1) The alkaline-permanganate method should be considered an aid to vegetation 

 tests rather than a substitute for them." 



H. J. Wheeler, in discussing this subject, questioned the accuracy 

 of the results of vegetation tests for availability of nitrogen in dried 

 blood. 



The referee for the ensuing year was instructed to further test the 

 permanganate method. 



Potash. — The report on potash was submitted by C. H. Jones. This 

 report recorded the results obtained by 9 analysts in a comparison of 

 the present Liudo-Gladding and optional methods for the determina- 

 tion of water-soluble and acid-soluble potash in wood ashes and cotton- 

 hull ashes, as well as the results of tests of methods for determining 

 chloriu in fertilizers. 



The results indicated that these methods are accurate and reliable 

 for the determination of potash in ashes. It is necessary, however, in 

 the Lindo-Gladding method to see that the potassium-platinum precipi- 

 tate is perfectly soluble in water. 



B. B. Ross called attention to the fact that certain kinds of asbestus 

 are attacked and dissolved to an appreciable extent by the ammonium 

 chlorid solution used in washing the potassium-platinum precipitate. 



The referee recommended the following method for determining 

 chlorin in fertilizers, which has been used at the Vermont Station with 

 satisfactory results for several years. To 50 cc. of the Lindo-Gladding 

 solution for potash (equivalent to 1 gm. of original substance), add an 

 excess of nitric acid and as many cubic centimeters of silver nitrate 

 solution (1 cc. of which corresponds to chlorin equivalent to 1 per cent 

 of potash, K 2 0, on a basis of 1 gm. of substance) as the percentage of 

 K 2 Q found +0.5 per cent; boil the solution for about 5 minutes, stir, 



1 Vermont Sta. Rpt. 1898, p. 171. 



