4C6 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



The proof of the correctuess of these figures is plain : 



Sohible phos. acid, 200 lbs., ® 12i cents, would cost $25 00 



lijsoluble " " 50 lbs., ® 5 " " " 2 50 



Mtrogent 60 lbs., ©201 " " " 32 50 



Total valuable ingredients in ton would cost $40 00 



Another method for calculating the costs of ingredients, which con- 

 sists in estimating the value of one at an assumed rate per pound, sub- 

 tracting its total value, as thus computed, from the whole cost, and divid- 

 ing the remainder by the number of pounds of the other ingredients to 

 get the cost of the latter, is too simi^le to require further explanation 

 here. 



In valuations current in this country, nitrogen in these substances has 

 been reckoned as worth all the way from two to five times as much as 

 phosphoric acid, pound for pound. Considering the fact that the nitro- 

 gen is generally in quite readily, and the phosphoric acid often in very 

 slowly available forms, there is ground for varying ratios. A full dis- 

 cussion of this subject would require more space than either the knowl- 

 edge at our disposal or the necessary limits of this article would per- 

 mit. In brief, however, I do not find it easy to see why, if nitrogen is 

 worth only about twice as much as phosphoric acid, pound for pound, 

 when both are in their most available forms, it should be worth three or 

 four times as much, as is sometimes assumed, in bone, in which both 

 occur in much less available forms. Too little is known a!t present of 

 the effect of decomposing nitrogenous matter in bone, fish, castor pom- 

 ace, and the like, in dissolving, diffusing, and otherwise rendering avail- 

 able the phosphates with which it is so intimately connected, to enable 

 us to form any accurate estimate of its value on this account. I con- 

 fess that in the light of the little knowledge that we do have it seems 

 to me more just to preserve ratios of valuation of nitrogen and phos- 

 phoric acid in bone the same, or nearly the same, as in the most avail- 

 able forms. In fish, animal refuse, and otlier materials which contain 

 considerable nitrogenous matter other than that so intimately mingled 

 with the phosphate, and in a form probably more ready to decompose, 

 it seems reasonable to give the higher relative value to nitrogen. 



In view of such considerations as these, the costs of nitrogen and 

 phosphoric acid in the tables in this report have been calculated on the 

 basis of ratios as follows : 



In fish, slaughter-house refuse, and castor-pomace — Nitrogen : Phos- 

 phoric acid:: 2.^ : 1. 



In bone — Nitrogen : Phosphoric acid:: 2 : 1. 



In superphosphates the costs of the ingredients are calculated on a 

 basis of ratios as per the valuations used in the last report of the sta- 

 tion, to wit: Nitrogen, 25; phosphoric acid, soluble in water, 15; solu- 

 ble in ammonium citrate, 10 ; insoluble, 6. 



