CHAPTER XIII 



ON THE EXAMINATION OF COMMERCIAL FER- 

 TILIZERS AND MATERIALS 



THE methods here given necessarily include 

 the examination of material used in the manu- 

 facture of fertilizers. 



Moisture. Inasmuch as the percentage of 

 moisture in a fertilizer may vary considerably 

 under the conditions to which it is exposed, 

 a determination of moisture is always imperative, 

 in order that the results on other constituents 

 as determined by different analysts, say those of 

 the buyer and the seller, may be fairly compared. 



Some analysts invariably heat to a certain 

 temperature (100 to 110 C.) until a constant 

 weight is obtained; others heat for a certain 

 time, 2, 3, or 5 hours, and call the loss moisture. 

 The plan prescribed by the Association of Official 

 Agricultural Chemists is probably most uni- 

 formly followed. That is as follows: 



For alkaline salts, heat 1 to 5 gms. at 130 

 to constant weight. 



For other material, heat 2 gms. (or 5 gms. 

 if the sample be coarse) for five hours at 100. 

 The loss in either case is taken as representing 

 moisture. 



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