No. 7. DEPARTMENT OF AGRICULTURE. 677 



Comparison of Selling Price and Valuation, 1902-1908— Continued. 



Ground bone: 

 iy02, Spring, 

 Fall, 



1903, Spring, 

 Fall, 



1904, Spring, 

 Fall. 



1905, Spring, 

 Fall, 



1906, Spring, 

 Fall, 



1907, Spring, 

 Fall, 



1908, Spring, 



B 

 O 



d <v 

 3 O 



"a 

 do 



^B 



X o 



—1.72 



— ..'iS 

 —1.42 



—.45 



— .50 

 .95 



—2.36 



l.<0 



—.79 



1.32 



—1.91 



— .12 



— .08 



FERTILIZER ANALYSES, AUGUST 1 TO DECEMBER 31, 1908. 



Since August 1, 1908, there have been received from authorized 

 sampling- agents eleven hundred and eighty-one fertilizer samples, 

 of which four hundred and eighty-eight were subjected to analysis. 

 Preference is given to those which have not vecently been analyzed. 

 In certain cases where two or more samples representing the same 

 brand were received, equal portions from the several samples were 

 united, and the composite sample was subjected to analysis. 



The samples analyzed group themselves as fellows: 285 complete 

 fertilizers, furnishing phosphoric acid, potash and nitrogen; 6 dis- 

 solved bones, furnishing phosphoric acid and nitrogen; 101 rock-and- 

 potash fertilizers, furnishing phosphoric acid and potash; 49 acidu- 

 lated rock phosphates, furnishing phosphoric acid only; 30 ground 

 bones, furnishing phosphoric acid and nitrogen, and 12 miscellaneous 

 samples, which group includes substances not properly classified 

 under the foregoing heads. 



The determinations to which a complete fertilizer is subjected are 

 as follows: (1) Moisture, useful for the comparison of analyses, for 

 indication of dry condition and fitness for drilling, and also of the 

 conditions under which the fertilizer was kept in the warehouse. (2) 

 Phosphoric acid — total, that portion soluble in water, and of the 

 residue, that portion not soluble in warm ammonium citrate solution 

 (a solution supposed to represent the ac'tion of plant roots upon 

 the fertilizer), which is assumed to have little immediate food value. 

 By difference, it is easy to compute the so-called "reverted" acid, 

 which is the portion insoluble in water but soluble in the citrate. 

 The sum of the soluble and reverted is commonly called the "avail- 

 able" phosphoric acid. (3) Potash soluble in water — most of that 

 present in green sand marl and crushed minerals, and even some of 

 that present in vegetable materials such as cotton-seed meal, not 

 being included because insoluble in water even after long boiling. 

 (4) Nitrogen — This element is determined by a method which simply 



