38 THE CONNECTICUT AGRICULTURAL 



The chemicar and mechanical analysis of a sample of ground 

 bone being before us, we separately compute the nitrogen value 

 of each grade of bone which the sample contains, by multiplying 

 the pounds of nitrogen per ton in the sample by the per cejit. of 

 each grade, taking yoT^^ ^^ *^^^ l^roduct, multiplying it by the 

 estimated value per pound of nitrogen in that grade, and taking 

 this final product as the result in cents. Summing up the separate 

 values of each grade, thus obtained, together with the values of 

 each grade for phosphoric acid, similarly computed, the total is 

 the estimated value of the sample of bone. 



The following example will serve for illustration. Rogers and 

 Hubbard's Pure Ground Bone, 818, contains nitrogen 3.94 per 

 cent., or 78.8 pounds per ton ; phosphoric acid 22.50 per cent., or 

 450 pounds per ton. The mechanical analysis showed : 



31 per cent. fine. 

 25 " fine medium. 



23 " medium. 



21 . " coarse medium. 



" coarse. 



100 



The calculations are as follows : 



78.8 X 31 -^ 100 X 17 = $4.16 

 78.8 X 25 ^ 100 X 15 = 2.96 

 78.8 X 23 -=- 100 X 14 = 2.54 

 78.8 X 21 -^ 100 X 13 = 2.15 



Estimated value of nitrogen, $11.81 



450 X 31 -^ 100 X 6 = $8.37 

 450 X 25 -^ 100 X H = 6.19 

 450 X 23 -=- 100 X 5 = 5.18 

 450 X 21 -^ 100 X H = 4.25 



Estimated value of phosphoric acid, $23.99 



$35.80 



The result agrees with the cost ($35.00) within 80 cents. 



When the sample of bone contains foreign matters introduced 

 as preservatives, dryers or adulterants, such as salt, salt-cake, 

 niter-cake, ground oyster-shells, spent lime, plaster, or soil, these 

 must be taken account of in the mechanical analysis, especially 

 since they would be likely, on sifting, to pass chiefly or entirely 



