IRON. 151 



% 



As shown by this formula, some sulphuric acid is set free, 

 winch has a dissolving action on the ferrous phosphate; to 

 prevent which, sodium acetate may be added forming sodium 

 sulphate and free acetic acid, which latter does not act as a 

 solvent. 



Ferric hypophosphite, Ferri hypophosphis, Fe,6H 2 P0 2 = 501.8 



(Hypophosphite of iron). Made by dissolving ferric hydrate in 

 hypophosphoric acid, and evaporating. It is a grayish-white 

 powder, insoluble in water, soluble in hydrochloric acid. 



Scale compounds of iron. Quite a number of officinal prepara- 

 tions of iron are made by mixing solution of ferric citrate (ob- 

 tained by dissolving ferric hydrate in citric acid) with solutions 

 of other salts, evaporating them to the consistence of thick 

 8} 7 rup, spreading this on glass plates, and drying at a low tem- 

 perature, when the compounds are obtained in the form of thin, 

 translucent scales. 



While the Ferri phosphas of the U. S. P. of 1870 was the 

 above-mentioned ferrous phosphate, Fe 3 2P0 4 , the Ferri phosphas, 

 phosphate of iron, of the U. S. P. of 1880 is a mixture (or, most 

 likely, double compound) obtained by evaporation of a mixture 

 of ferric citrate and sodium phosphate. 



The ferric pyrophosphate of the U. S. P. is a similar scale com- 

 pound. Of others may be mentioned : Citrate of iron and am- 

 monia, citrate of iron and quinine, citrate of iron and strychnine, 

 etc. In some cases, tartaric acid is used in place of citric acid, 

 as, for instance, in tartrate of iron and ammonium, tartrate of iron 

 and potassium, etc. 



Compounds of iron with organic acids will be more fully con- 

 sidered in connection with the acids themselves. 



The object of these various organic scale compounds of iron 

 is, doubtless, to present otherwise insoluble iron compounds in 

 a soluble and convenient form for administration. 



