74 MATERIA MEDIC A AND THERAPEUTICS. 



-f- 4H 2 + 2NO. Introduced only for making several 

 preparations. 



Characters. Dark brown, inodorous and astringent. 



From Liquor Ferri Persulphatis are made : 



a, Ferri Oxidum Magneticum. Magnetic Oxide 

 of Iron. Fe 3 O 4 , with some peroxides. 



Sources. Made by precipitating a solution of 

 the Proto- and Persulphates of Iron with a Solution 

 of Soda, and drying. (1) FeS0 4 + Fe. 2 3S0 4 + 

 8NaHO = Fe2HO + Fe 2 6HO -f 4Na 2 S0 4 . (2) 

 Fe2HO -I- Fe 2 6HO = Fe 3 O 4 .4H 2 0. 



Characters. A brownish-black tasteless powder. 



Impurity. Metallic iron; detected by effer- 

 vescing with HC1. 



Dose. 5 to 10 gr. 



B. Ferri Peroxidum HumitJnTn, Moist Per- 

 oxide of Iron. Fe 2 .6HO. 



Source. Made by precipitating Solution of 

 Persulphate of Iron with Solution of Soda. Fe 2 3S0 4 

 + 6NaHO = Fe 2 6HO + 3Na 2 S0 4 . 



Characters. A soft reddish-brown mass. 



Impurities. Ferrous hydrate. Ferric oxy- 

 hydrate ; insoluble in cold HC1. 



Dose. 5 to oz. 



From Ferri Peroxidum Humidum is made : 



Ferri Peroxidum Hydratum. Hydrated 

 Peroxide of Iron. Fe 2 2 2HO. Made by drying 

 the Moist Peroxide. A reddish-brown powder, 

 without taste. Dose, 5 to 30 gr. 

 Impurities. Ferrous hydrate. 



Preparation. 



Empla strum Ferri. "Emplastrum 

 Eoborans." 1 in 11. 



From Ferri Peroxidum Hydratum is 

 made : 



Ferrum Bedactum. Reduced 

 Iron. Metallic iron, with a variable 

 amount of Magnetic Oxide. 



Source. Made by passing dry 

 Hydrogen over the Hydrated Peroxide. 



Characters. A fine greyish-black 

 powder. 



