GERMAN METHOD 21 



as would be the case, for instance, with superphosphates. With 

 these, which are often in a state more or less agglomerated, it is 

 recommended to introduce, in order to divide them, a certain 

 quantity of calcium sulfate to reduce them to a pulverulent state. 



In the case of animal debris they should be divided as finely 

 as possible with the aid of scissors and then passed through a 

 drug mill if dry enough. They are then mixed by hand and 

 may finally be obtained in a state of considerable homogeneity. 



When fertilizers are in a pasty state or more or less liquid, they 

 are dried at 100, first introducing a little oxalic acid in case 

 they contain any volatile ammoniacal compounds. The product 

 of desiccation is then passed through a mill. Before treating in 

 this way it is necessary to be sure that the composition will not 

 be altered by drying. In the case of a mixture containing super- 

 phosphates and nitrate, for instance, drying would eliminate the 

 nitric acid. In such a case the free phosphoric acid should be 

 neutralized with a base like lime. In the case of fertilizers con- 

 taining both nitrates and volatile ammoniacal compounds, the 

 addition of oxalic acid might also set free nitric acid during the 

 desiccation. In such a case it is necessary to dry two samples ; 

 one with the addition of oxalic acid for the purpose of estimating 

 the ammonia, and the other without the acid for the purpose of 

 estimating the nitrate. A qualitative analysis should precede 

 all the operations so as to determine the nature of the material 

 to be operated on. 



27. German Method. In the method pursued by the German 

 experiment stations the manipulation is conducted as follows : 10 



(1) Dry samples of fertilizers must be passed through a sieve 

 and afterwards well mixed. 



(2) With moist fertilizers, which can not be subjected to the 

 above process, the preparation should consist in a careful and 

 thorough mixing, without sieving. 



(3) On the arrival of the samples in the laboratory their 

 weight should be determined. The half of the sample is pre- 

 pared for analysis and the other part, to the amount, at least, of a 

 kilogram, should be placed in a glass vessel, closed air-tight, and 



"Die landwirtschaftlichen Versuchs-Stationen, 1891, 88 : 303. 



