OF IRON. 331 



tosulphate of iron were dissolved in water, and 

 the oxide peroxidized by digesting the solution 

 with a little nitric acid. After the peroxidation 

 was completed, I saturated the excess of nitric 

 acid still remaining, as nearly as possible, by am- 

 monia, and added a solution of 315 grains 

 (equivalent to 15 atoms) of phosphate of soda. 

 After the perphosphate of iron had subsided, I 

 found that the residual liquid still contained iron, 

 owing to an excess of nitric acid which it still 

 contained ; but on adding a few drops of am- 

 monia, a little perphosphate of iron precipitated, 

 and the liquid was now perfectly free from iron. 

 The perphosphate of iron thus obtained, was 

 dried on the filter in a gentle heat; when it 

 ceased to lose weight it was weighed, and then 

 exposed to a red heat ; the loss of weight was 

 noted, and considered as water. The anhydrous 

 salt was now composed of peroxide of iron and 

 phosphoric acid. 



The peroxide of iron from 173*75 grains of 

 protosulphate of iron is 50 grains ; the phospho- 

 ric acid in 315 grains of phosphate of soda is 

 52*5 grains. Now, the anhydrous salt only ex- 

 ceeded 102*5 grains by about 2 grains ; hence, 

 it is evident that the anhydrous salt is a perses- 

 quiphosphate of iron. 19*25 grains of the salt, 

 as dried on the filter, when exposed to a strong 

 red heat, underwent a kind of semifusion, and 



