G-4 MODERN 11 1U11 FARMING. 



It is, however, as the foregoing analyses show, uot very frequently 

 met with in a high state of purity, but generally contains certain 

 portions of iron and alumina, besides being mixed up with quantr 

 ties of an inert kind of ganguc, from which its separation (by hand 

 work) is arduous and costly. 



These phosphates are extremely hard and difficult to grind, and 

 may be said to contain no carbonate of lime. Their percentage of 

 iron and alumina is not sufficiently high to militate against their sat- 

 isfactory decomposition, but what causes them to be regarded with 

 disfavor, is their variable, but always considerable proportion of 

 fluorine, which, upon being brought into contact with sulphuric 

 acid in the manufacturing process, generates large volumes of most 

 irritating and poisonous vapors of hydrofluoric acid. 



The great inconvenience and danger arising from this cause, can 

 only be obviated by bringing the acid to bear upon the mineral and 

 effecting its decomposition, in well-closed mixers. If these mixers 

 are provided with proper ventilating shafts, to carry off the gases as 

 soon as they are set free, no cause for apprehension will any longer 

 exist, and the material will yield the most satisfactory results, 



A large majority of manure producers in this country have, how- 

 ever, hesitated to make the needful changes in their plant, and have 

 preferred the use of South Carolina phosphates, as offering much 

 less difficulty from an industrial, and yet excellent results from a 

 commercial point of view. In consequence of this policy the 

 greater portion of Canadian apatites have always been, and still are, 

 shipped to England, whence they very frequently come back to 

 America as superphosphates of lime. It is to be devoutly hoped 

 that the rapid progress now being made in all the arts throughout 

 the United States, will shortly induce the larger manufacturers to 

 reconsider their policy and make more use of this excellent and high 

 grade phosphate. 



Why should American farmers bear the enormous loss represented 

 by the cost of freight from Montreal to English ports, and from 

 thence back again to their own ; amounting in the aggregate on the 

 manufactured article to a total of seven or eight dollars per ton ? 



