300 METALS AND THEIR COMBINATIONS. 



Solution of ferric subsulphate, Liquor ferri subsulphatis 

 (Mouses solution). This is a solution similar to the preceding, but 

 contains less sulphuric acid, and is, therefore, looked upon as a basic 

 ferric sulphate, of the doubtful composition 5[Fe 2 (SO 4 ) 3 ].Fe 2 (OH) 6 . 



Ferrous carbonate, PeCO 3 . Occurs in nature; maybe obtained 

 by mixing solutions of ferrous sulphate and sodium carbonate or 

 bicarbonate : 



FeS0 4 + 2NaHC0 3 = NaJSO, -f FeCO 3 + CO 2 + H 2 O. 



The precipitate is first nearly white, but soon assumes a gray color 

 from oxidation. The saccharated ferrous carbonate, U. S. P., is made 

 by mixing the washed precipitate with sugar, and drying. The 

 sugar prevents, to some extent, rapid oxidation. The preparation 

 contains 15 per cent, of ferrous carbonate. 



Ferric carbonate does not exist, the affinity between the feeble ferric 

 oxide and the weak carbonic acid not being sufficient to unite them 

 chemically. 



Ferrous phosphate, Fe 3 (PO 4 ) 2 . When sodium phosphate is 

 added to solution of ferrous sulphate, a precipitate of the composi- 

 tion FeHPO 4 is formed : 



NajHPO^ + FeSO 4 = FeHPO 4 + Na.jSO 4 . 



If, however, sodium acetate is added, a precipitate of the composi- 

 tion Fe 3 (PO 4 ) 2 is formed : 



3FeSO 4 + 2N02HPO4 = Fe 3 (PO 4 ) 2 + 2Na 2 SO 4 -f H 2 SO 4 . 



The sulphuric acid liberated, as shown in this formula, decomposes 

 the sodium acetate, forming sodium sulphate and free acetic acid. 

 Ferrous phosphate is a slate-colored powder, absorbing oxygen 

 readily, becoming darker in color. 



Ferric phosphate, FePO 4 , may be obtained from ferric chloride 

 solution by precipitation with an alkali phosphate. The Soluble ferric 

 phosphate and the Soluble ferric pyrophosphate of the U. S. P., are 

 scale compounds. (See index.) 



Ferric hypophosphite, Ferri hypophosphis, Fe(H 2 PO 2 ) 3 = 

 249.09 (Hypophosphite of iron). It is obtained by adding a solution 

 of sodium hypophosphite to a solution of ferric chloride or sulphate, 

 free from excess of acid. The precipitate is filtered, washed, and dried. 

 It is a grayish-white powder, slightly soluble in water, soluble in 

 hydrochloric acid, in hypophosphorous acid, and in a warm, concen- 

 trated solution of an alkali citrate. 



