COST OF SOLUBLE PHOSPHORIC ACID. 387 



material into a good, fine mechanical condition, and cany 

 out the chemical processes involved in their manufacture with 

 the best skill. 



To manufacture, in the old-fashioned way, only low-grade 

 ammoniated superphosphates, causes, as a general rule, not 

 less expenditure for labor, etc., than to apply more efficient 

 grinding, mixing and drying apparatus for the preparation of 

 the higher grades. A minute division of the crude phosphates, 

 before subjecting them to the action of sulphuric acid, is essen- 

 tial for a successful reaction. A subsequent uniform fine 

 pulverization of the entire mass is the first requisite for a 

 desirable general distribution and thus speedy action on the 

 crops. 



Artificial commercial fertilizers are, in the majority of cases, 

 only applied to supply special wants, and are expected to act 

 soon ; besides, they are too high-priced to render their appli 

 cation profitable, in case years have to pass by before they 

 return with interest the capital invested. It is for this reason 

 that I advise farmers not to buy coarse articles, except at a 

 very reduced price. Again, the expenses of handling and of 

 carrying low grades of fertilizers increases the cost of their 

 essential ingredients — being only a small part of the bulk — 

 quite frequently at a rate of several cents per pound, as com- 

 pared with the higher grades. 



The following abstract of a late market report on "Com- 

 mercial Fertilizers," from abroad, leaves no doubt about the 

 points just previously discussed. 



The price of one pound of soluble phosphoric acid has 

 varied during the past year from 12.95 cents (currency) to 

 25.60 cents (currency). These variations were noticed to 

 stand in a certain relation to the concentration of the super- 

 phosphates sold. The highest price was paid in the low 

 grades, the lowest in the high grades ; namely : 



In case of superphosphates containing, from — 



20 to 18 per cent, of soluble acid, 12.95 cents per pound. 



17 to 15 " " " 13.20 " 



14 to 12 " " " 14.35 " " 



10 to 8 " " " 19.07 " " 



7 to 5 " " " 25.60 " " 



