274 EXPERIMENT STATION RECORD. 



instructed to iucliule in the plan of work for the coming year a test of 

 this method with a variety of phosphatic materials. 



Slight changes were made in the method, as follows: In the precipi- 

 tation of the phosphoric acid by molybdic solution the time of digestion 

 is increased from 6 minutes to 10 to 15 minutes, and in the washing 

 of the precipitate the directions now provide that it shall be washed 

 5 or 6 times, the total washings amounting to from 150 to 250 cc. 



The reporter was also instructed to investigate methods for the 

 determination of iron and alumina in phosphates and of x)hosphoric 

 acid in slags. 



(2) Xitrogen. — J. P. Street reported results of comparative tests by 

 17 chemists of the Ulsch-Street, zinc-iron, and "Fassbender" methods, 

 in addition to trials of the modified Kjaldahl and Gunning methods and 

 determinations of ammonia by distillation with magnesium oxid. The 

 results by the Ulsch-Street method in the hands of different chemists 

 were not altogether satisfactory, a number of analysts reporting that 

 for some unexplained cause the method had given wholly unreliable 

 results in some cases, especially on pure nitrates. On the other 

 hand, others reported perfectly satisfactory results in a large number 

 of determinations of nitrogen in a great variety of fertilizing materials. 

 The results as reported by the zinc-iron method were also unsatisfac- 

 tory. The so-called "Fassbender" method gave good results on the 

 samples used in these tests. 



Tests by the Xew Jersey and Virginia stations of the solubility of 

 organic nitrogen in acid pepsin solution and by the Hayes permanga- 

 nate method were reported, together with pot tests of the organic 

 nitrogen by the Connecticut State Station. It was decided by the 

 Association that the Ulsch-Street, " Fassbender," and Hayes perman- 

 ganate methods should be further tested. The reporter was also 

 instructed to inquire into the origin and correct name of the so-called 

 "Fassbender" method. 



It was recommended that wherever possible or necessary in reporting 

 the results of analyses of fertilizers the forms of nitrogen should be 

 given; that the ferrous sulj)hate and sulphuric acid test for nitric 

 nitrogen should be used in case of fertilizers supposed to contain 

 nitrates; that the Schulz-Tiemann and Ulsch-Street methods for nitric 

 nitrogen be compared; and that in determination of ammonia 5 gm. or 

 more of freshly calcined magnesium oxid be used. 



A paper on "Comparison of nitrogen determination by the Kjeldahl 

 method distilling with and without j^otassium sulphid" was presented 

 by W. S. Sweetzer. The results of comparative tests on 53 samples of 

 miscellaneous fertilizing materials indicate that it is unnecessary to add 

 the sulphid, especially when copper flasks are used. 



(3) Potash. — A. L. Winton reported comparisons by 8 chemists of the 

 Lindo-Gladdiug and the optional methods for determining potash on 

 chemically pure and commercial muriate of potash and sulphate of 



