674 



ANNUAL REPORT OF THE 



Off. Doc. 



the j)resence of nitrogen and phosphoric acid in the proportions cor- 

 responding to tliose of bone is not proof positive that they have been 

 suj)])lied by bone. Finally, the differences in the iron arid silica con- 

 tent of bone and rock respectively, afford means of distinction useful 

 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 inf alible; they are 

 not designed to be used for close comparisons of single brands, but 

 only to indicate whether the price asked for a fertilizer is abnormal, 

 assuming good quality for the ingredients used. From this it is 

 clear that, except as high freiffhfs may require, the selling price of 

 a 'brand should not far exceed the valuation; hut that a fertilizer 

 may he made of inferior materials and yet have a high valuation. 



The valuations used during 1910 were modified for use during 1911 

 in accordance with the changes in wholesale prices of fertilizing 

 ingredients and to make the valuations more closely follow the sell- 

 ing price. 



The following comparative statement shows t'le valuations and 

 selling prices of the several classes of fertilizers during 1906 to 1910: 



Fertilizers. 



Spring, 1906. 



Oomplete, - 



Bock-and-potash, 



Dissolved bone, 



Ground bone, 



Dissolved rock, 



Fall. 1906. 



Oomplete, -- 



Rock-and-potash, 



Dissolved bone, 



Ground bone, - 



Dissolved rock, - 



Spring, 1907. 



Oomplete, 



Rock-and-potash, _ 



Dissolved bone, 



Ground bone, - 



Dissolved rock, -. - 



FaU, 1907. 



Oomplete, 



Rock-and-potash, 



Dissolved bone, 



Ground bone, - 



Dissolved rock, 



a 



c 



A 



o d 



^ O 



1.21 



—.99 



—1.75 



—.79 



—.77 



1.19 



—.70 



8.27 



1.32 



— .46 



2.24 



—.31 



2.80 



—1.91 



.08 



1.88 

 —.76 



5.52 

 .12 

 .09 



