514 ANNUAL REPORT OF THE OfE. Doc. 



Potash soluble in water — most of that present in green sand marl and 

 crushed minerals, and even some of that present in vegetable mater- 

 ials such as cotton-seed meal, not being included because insoluble 

 in water even after long boiling. (4) Nitrogen — This element is 

 determined in such manner as to ascertain its total quantity and 

 also, the quality of the organic nitrogenous material present in the 

 finished fertilizer. The fertilizer is washed thoroughly with water, 

 which removes the nitrates, ammonium salts and almost all of the 

 cyanamid nitrogen, and the soluble organic nitrogenous materials. 

 These are not separately determined but are grouped under the name 

 ''water-soluble nitrogen." The quantity of water-insoluble nitrogen is 

 directly determined, and by difference between its amount and the 

 total nitrogen, the water-soluble nitrogen is calculated. Another 

 portion of water-soluble material* is treated with alkaline potas- 

 sium permanganate, which attacks the nitrogenous organic sub- 

 stances present, and converts the more active portion into am- 

 monia, which is distilled off, determined, and its nitrogen calcu- 

 lated as "active insoluble nitrogen." The "inactive insoluble nitro- 

 gen" is then computed by substracting the active insoluble from the 

 total insoluble nitrogen. The term "available nitrogen" as used 

 in this report, is the sum of the water-soluble and the active insol- 

 uble nitrogen. It is equivalent to the total niitrogen less the inactive 

 insoluble nitrogen. In high grade organic nitrogenous materials, 

 among which, from its behavior with this treatment, must be included 

 horn meal, the percentage of inactive nitrogen in the insoluble 

 nitrogen is usually under 40 per cent. ; and the ratio of inactive 

 to active insoluble nitrogen in such materials is usually less than 

 GO :100. On the other hand, in the case of low-grade nitrogenous ma- 

 terials, the proportions of inactive nitrogen are much higher. The 

 separations effected by these methods are therefore of great value 

 in distinguishing whether the insoluble nitrogen is derived from high 

 grade materials, or from low grade substances such as garbage tank- 

 age, peat, mora meal, uncidulted hair, leather, etc. There is, how- 

 ever, one fertilizer ingredient rapidly coming into use, whose pres- 

 ence may lead to erroneous conclusions, if judgment is based solely 

 upon the facts ascertained by the foregoing method, namely, cyana- 

 mid. This substance contains from 13 to 16.5 per cent, of nitro- 

 gen, of which 12 to 14.7 per cent, is soluble in water, by the mode 

 of treatment used in the alkaline permanganate method; and, of the 

 1,0 to 1.7 per cent, of water-insoluble nitrogen, less than one-fifth is 

 active; so that the ratio of inactive to insoluble nitrogen is about 

 80:100. Owing to its tendency to reduce the availability of the 

 phosphoric acid in acid phosphate mixtures, limited quantities only 

 of this ingredient can be used advantageously in mixed fertilizers. 

 Nevertheless, in cases where low grade sources of nitrogen are in- 

 dicated by the foregoing method, it would be needful to determine, 

 by supplementary tests, whether or not cyanamid may be present to 

 account for an undue proportion of inactive, insoluble nitrogen, 

 before concluding that such excess of inactive nitrogenous material 

 is attributed to low-grade nitrogenous constituents. It is desir- 

 able to keep in mind at this point the fact also that certain widely 

 used low-grade nitrogenous substances, such as garbage tankage, 

 peat and mora meal, are not included in the list of substances whose 



•This determination Las been omitted in all cases where the insoluble nitrogen Is only 2 per 

 cent, or less. 



