ELISHA MITCHELL SCIENTIFIC SOCIETY. 2J 



THE EFFECT OF PULVERIZATION ON FERTIL- 



IZER SAMPLES. 



H. B. BATTLE. 



That a sample of eoiumercial fertilizer should be finely ground is 

 not to be doubted. The necessity is more apparent in an ammoni- 

 ated guano than in an acid phosphate, for with the former, where 

 three or four ingredients enter into its constitution and too with 

 properties so entirely different, it is extremely difficult to obtain a 

 fair and impartial sample unless these constituents are finely ground 

 and carefully mixed. 



In a chemical analysis where the amount used is small, only two 

 grms., in the more important determinations, all the accuracy pos- 

 sible is needed to procure a result that will represent the whole mass. 

 It is customary that the sample shall be ground so as to pass a 20 

 mesh sieve, i. e., a sieve with 20 meshes to the linear inch or each 

 mesh is -^^ inch square nearly. The meaning of this is not that each 

 particle is ^V inch square — for possible \ of the sample may pass in 

 turn a 40 mesh and some even a dO mesh without further grinding 

 — but that none of the particles are coarser than ^\j inch square. 



In an ammoniated fertilizer the nitrogenous materials, as horn or 

 hoof, being tougher are disintegrated and pulverized with most dif- 

 ficulty, while the phosphatic constituents with particles even harder 

 are ground much finer, friction between the particles themselves as- 

 sisting in the action. If such a fertilizer, after being ground to pass 

 a 20 mesh seive and bottled, is even slightly shaken the finer parti- 

 cles of phosphate settle to the bottom, leaving the coarser nitroge- 

 nous mass at the surface, and a sample from the top will give a re- 

 sult to some extent at variance with that lower down. This settling 

 is the more noticeable when the moisture is not present in large 

 amount. Finer pulverization then is absolutely necessary to secure 

 the best results. But besides giving a more uniform mass there are 

 other results connected with finer grinding which I have endeavored 

 to show in the present paper. 



For comparison, both acid phosphates and ammoniated fertilizers 

 were taken and each sampled after being passed through sieves of 

 20, 40, 60 and 100 meshes to the linear inch. 



A. Is a high grade acid phosphate. 



B. A medium grade acid phosphate. 



C. An ammoniated guano. 



