89 



Tli- work of 'Present <.n potassium nitrate is reported separately, as follows: 



(15) BY METHOD (D). 



(Hi) BY METHOD (C,). (ULSCII-STHEET.) 



Impurities in n , konc.l >n the nitrogen as the basis of percentage, were 



^ported as follows ly two analysts only: 



fjiuriti,* in rmgents based on nitrogen present. 







Method. 



< ( .M MK.vr 18 Y ANALYSTS. 



Carpenter, reporting the work of <'<<>ke, says: 



Th> Kji-ldahl im-ihod, or in fan any of the methods described in the "Official 

 Methods of Analysis," are very unsatisfactory for the determination of nitrates. In 

 our own work for tin- analysis of nitrate of soda, nitrate of potash, etc., we use an 

 method. 



Robb says: 



[lil.l.- !..<> of nitric oxid when I added the salicylic-acid 



mixture both in li the nitric-acid solutions containing a nitrate-free fer- 



tili/.iT ami ih-.-e containing cane sugar. 



Rudnirk says: 



InasmiK li as all of the work could not be carried out in full, such features as seemed 

 to me of less interot from the stand |>oint of a fertilizer manufacturer's laboratory 

 omittcil. These had to do chiefly with the determination of nitrate nitrogen 

 I" i -' W* are not o much interented'in this feature, inasmuch as there are several 

 good methods now in u>- for this purpose. Of these we prefer the Schloesing- Wagner 

 method, as described in Bulletin 107 of the Bureau of Chemistry, page 111. 



It is not the determination of nitrate nitrogen that we are so vitally interested in 

 but tin- determination of total nitrogen where nitrates are present. 



The results with the tilth-normal nitric acid were very unsatisfactory indeed. 

 This was probably due to the great dilution with water, which we never meet with 

 in our work. Every precaution was taken to prevent undue heating on adding the 

 strong saiiryl-sulphonic acid. 



A great many more determinations than appear in the preceding report were made 

 in this laboratory, but none of them was any more satisfactory than those reported 

 on, and there seemed to be no special significance in the results obtained. The Ulsch 

 met hi M I as -iven in Bulletin 107 with a number of variations has been tried in this 

 laboratory at various times during the past years, but has never given satisfactory 



