DEYING AND ENEICHMENT OF PHOSPHATES. 65 



phate of ammonia dissolved in 400 c.c. of hot water, and then to 

 add 800 parts of sulphuric acid of 53° B. A violent reaction ensues, 

 the mass intumesces and heats to 110° C. After an hour it solidifies 

 .and is easily ground ; it contains 18 per cent of phosphoric acid, 

 two-third^of which are soluhle in water. This process is interesting ; 

 moreover, it is simple, and yields good results ; it might he advan- 

 tageous to use it in the manufacture of phosphate of ammonia, if 

 the raw materials were to be got cheap. Besides, this process seems 

 to preclude the retrogradation of the soluble phosphoric acid.^ 



10. Glaser manufactures precipitated phosphates from insoluble 

 phosphates of alumina, by treating the latter with a cold alkaline 

 solution or with a hot concentrated solution of alkaline carbonate. 

 In this operation the phosphate of alumina is dissolved. In using 

 the alkaline solution, the liquid separated from the residues is 

 treated with carbonic acid. If a hot solution of alkaline carbonate 

 be used, it is cooled, and the dissolved phosphate of alumina is 

 precipitated. The solution is then used for a new operation. But 

 from tests made, raw phosphate of alumina does not dissolve in 

 a hot solution of alkaline carbonate. 



11. Peternmnn of Gembloux recommends treating the raw 

 phosphate at a high temperature, to convert the phosphoric acid 

 into a very soluble form. Bazin has based a British patent No. 

 15,237 on this principle. He heats phosphates in retorts to a 

 temperature of 1300° to 1500° C. 



12. Hodgkins (American patent No. 423,320, 1890) mixes the 

 phosphate in fine powder, with quicklime, which he then slakes. 

 But it is not easily seen how that treatment can render phosphates 

 more soluble. Besides, no field experiments appear to have been 

 made to bring out the value of the resultant manure. 



Manufacture of Precijnfated Pliosphate by Electrolysis.—.^ new 

 method of manufacture, based on electrolysis, has been invented 

 by Prof. W. Palmer of Stockholm. It consists in converting the 

 raw phosphate by the wet w^ay into a readily assimilable form, 

 and that at the ordinary or a slightly elevated temperature. The 

 raw material is ground apatite. It need not be finely ground. In 

 an apparatus specially constructed for the purpose, a solution of 

 chlorate or perchlorate of soda is electrolyzed, which disengages 

 free chloric acid, sometimes even perchloric acid, in the anode cell. 

 The acid anode liquid is made to react on the raw phosphate in a 

 battery of wooden cases, fitted with perforated bottoms, so that the 

 solvent first comes in contact with almost exhausted apatite. 

 The alkaline liquid from the cathode is added to the saturated 



iBut it is evident on the face of it that such generalizations are futile. 

 The data given can only have been applicable to the particular phosphate to 

 which Carr applied it. All phosphates rich in oxides of iron and alumina 

 nvould not respond to such treatment so as to yield the above results. 



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