Chemical Analyses of Fertilizers 185 



against the use of certain kinds of good materials, and 

 in favor of certain kinds of poorer materials. That is, 

 a valuation of 2 cents a pound for insoluble phosphoric 

 acid in complete fertilizers, for example, is a direct encour- 

 agement to include in the mixture a considerable propor- 

 tion of the insoluble phosphoric acid from South Carolina, 

 and other rock phosphates, the value of which is ignored 

 in commercial transactions; while that price (2 cents) 

 does not give a fair value to the phosphoric acid contained 

 in bone, tankage and natural guanos, products in which 

 the commercial value of the insoluble is recognized, 

 that is, mixtures which contain bone and tankage, and 

 which furnish phosphoric acid largely in an insoluble form. 

 The valuation fixed for this form is too low to fully repre- 

 sent the commercial value of these goods. It is also said 

 that the trade value for available phosphoric acid in the 

 mixtures encourages the use of superphosphates from the 

 rock phosphates, and discourages the use of superphos- 

 phates from bone-black, bone-ash and dissolved bone, 

 because the trade or commercial values represent the 

 average cost of available phosphoric acid in the super- 

 phosphates from all of these, while the latter materials, 

 because of actual commercial conditions, cost more than 

 the superphosphates from the former. 



The chief arguments in favor are : 



First, that it is not asserted that the system shows abso- 

 lutely the commercial value of each brand at the time the 

 sales are made, but the comparative commercial value. 



Second. They are not misleading. The commercial 

 valuations are not intended to be a guide as to the agri- 

 cultural value of a fertilizer. It is distinctly stated in the 

 reports of analyses that the comparative values are 

 purely commercial. 



