MODERK HIGH 



There are consequently huge quantities of superphosphates, con- 

 stantly foisted upon the farmer, which, made in ignorance, purchased 

 in ignorance, and used in ignorance, sometimes produce satisfactory 

 results, but more frequently give no proportionate or immediate re- 

 turn for the money they have cost. 



If a thousand tons of phosphate of lime be given to one manufact- 

 urer, he will transform it into a fine and dry acid phosphate, in 

 which every particle of phosphoric acid has been made available; 

 and if the very same quantity of the same material be entrusted to 

 his next-door neighbor who to the uninitiated possesses the same 

 facilities he may very possibly turn out a moist, pasty substance, 

 in which more than half the phosphate will be found insoluble. 



As the readers for whom these pages are written are not supposed 

 to be producers, but consumers of manures, we shall not attempt to 

 discuss the reasons for the unfortunate lack of homogeneity; but 

 shall merely sketch out the process by which superphosphates 

 should be made, if they are to fulfill the conditions required by the 

 advocates of their application. 



Assuming ourselves to be dealing with the manufacture on a 

 large scale, and in connection with the production of sulphuric acid, 

 the first step to be taken is the reduction of the raw material to 

 a powder, rivaling in degree the finest wheaten flour. 



Various more or less efficient systems of pulverization have been 

 introduced and adopted, but it will serve no useful purpose to 

 describe them, the form of implement being of small importance 

 providing the object is attained. 



The finely ground material is generally turned directly into sacks, 

 weighed by mechanical agency, and laid aside ready for use. 



The mixture with the acid is performed in a commodious shed, 

 made to communicate with a high chimney or shaft, so as to carry 

 off the noxious vapors of fluoric, silicic and carbonic acids and 

 chlorine which are always more or less evolved by all phosphates 

 during the reaction. In the centre of the floor of this shed, should 

 be built, with a good foundation, a strong brick-work shell, divided 

 into four or six chambers or dens. 



