12 



AGRICULTURAL ANALYSIS 



are hot suitable for raw phosphate rock, coarse raw tankage, fish 

 scrap, farm manures, tobacco stems, unground kainit, nor for 

 very lumpy nitrate of soda and sulfate of ammonia, all of which, 

 except when mechanical devices are used, leave much to the judg- 

 ment of the sampler, and for which only general instructions can 

 be given. 



Large samples should be secured from five to ten per cent, of 

 the material, being careful to maintain the proper relation between 

 the coarse and fine portions, and to protect the sample from loss 

 or absorption of moisture. When the material is very wet, as fish 

 scrap, or may take up much moisture, as sulfate of ammonia, 

 the sample should be weighed and brought into an air-dry condi- 

 tion, and again weighed. It is now coarsely ground, thoroughly 



Kig. i. Apparatus for Crushing Mineral Fertilizers. 



mixed and a subsample taken, which may be again ground and 

 subsampled if necessary. The loss or gain in bringing to an air- 

 dry condition must be carefully noted and the results of the 

 analysis corrected thereby. 



15. Minerals Containing Fertilizing Materials. When possible, 

 the samples should be accompanied by a description of the mines 

 where they are procured and a statement of the geologic condi- 



