No, 6. DEPARTMENT OF AGRICULTURE. 875 



It is needful to note hero auothci- factor greatly alVecting the prac- 

 tical accuracy of these approximations. Their computation would 

 offer little dilUculty and their usefulness be far greater, if, by the 

 ordinary methods of analysis, the exact nature of the ingredients 

 used to supply the several fertilizer constituents, were capable of 

 certain determination. This is, however, possible, to-day, to only a 

 limited extent. The valuations are, therefore, based on'the assump- 

 tion that the fertilizers are uniformly compounded from high quality 

 ingredients, such as are commonly employed in the manufacture of 

 fertilizers of the several classes. Consumers should carefully avoid 

 the error of accepting such valuations as infallible; they are not de- 

 signed to be used for close comparisons of single brands, but only to 

 indicate whether the price asked for a fertilizer is abnormal, as- 

 suming good quality for the ingredients used. From this it is clear 

 that, except as high freights may require, the selling price of a 

 brand should not far exceed the valuation; but that a fertilizer may 

 be made of inferior materials and yet have a high valuation. 



The valuations used during 1901 were modified for use during 1902 

 in accordance with the changes in wholesale prices of fertilizing 

 ingredients and to make the valuations more closely follou^ the sell- 

 ing price. 



The following comparative statement shows the valuations and 

 selling prices of the several classes of fertilizers during 1900 to 

 1902: 



