132 The Phosphates of America. 



75 Ibs. phosphate of lime.. .X .625 require 46.88 Ibs. phosphoric acid. 

 7}^ Ibs. carbonate of lime.. X 1.690 " 12.68 " " 



3 Ibs. iron and alumina as 



oxides, say X3.000 " 9.00 " " 



So that the total phosphoric-acid solution 

 of 45 B. required to render 100 pounds 

 of the above phosphate soluble in neu- 

 tral citrate of ammonia is 68.56 pounds. 



This quantity being the known required minimum, it is easy 

 after one or two trials of the drying capacity of the mixture, to 

 increase it at will up to any desired limit, it being evident that the 

 more it is increased the greater will be the amount of " water-sol- 

 uble " phosphate produced ! 



The mixture, when made, is dropped, charge by charge, into the 

 " dens," where it very soon sets into a porous mass, not quite dry, 

 but sufficiently so to be easily dug out. This mass is cut up into 

 pieces of reasonable size and dried by hot air, in sheds constructed 

 for the purpose, in any form, or on any plan, that will facilitate 

 effective and rapid work. Directly it is sufficiently dryfor the 

 market it is put through a disintegrator and filled into bags. 



In Europe the great superiority of this method of dealing with 

 raw phosphates over the more generally established plan has been 

 recognized for some years, and the high-grade product is much in 

 vogue in Germany and France. The rough-and-ready plant which we 

 have outlined has been supplemented in those countries by much 

 labor-saving machinery in the form of mixers and filtering presses, 

 the majority of which are protected by patent and chiefly manu- 

 factured in Germany, at Halle an der Saale. For the purposes of 

 experimental demonstration, however, we have deemed it preferable 

 to dispense with a description of all costly foreign apparatus, feeling 

 that we may trust to the well-known genius of our American me- 

 chanical engineers for the construction of such plant as may be 

 necessary in different localities, and under varying circumstances. 

 When we bear in mind the proverbial conservatism of the farmer 

 and his distaste for innovations, we shall see the necessity for going 

 slow in this matter, for it will doubtless take some time to create 

 an active demand from his direction for a concentrated superphos- 

 phate. Meantime, however, those who are engaged in handling 

 fertilizers as middlemen will be more readily convinced, especially 

 when they appreciate the economy in transportation, if in nothing 

 else, which such a product will afford. How great this economy 



