174 METALS AND THEIE COMBINATIONS. 



Ferric phosphate, Fe 2 (PO 4 ) 2 , may be obtained from ferric chloride 

 solution by precipitation with an alkali phosphate. The soluble 

 ferric phosphate of the U. S. P. is a scale compound. (See index.) 



Ferric hypophosphite, Ferri hypophosphis, Fe 2 (H 2 PO 2 ) 6 = 

 501.8 (Hypophosphite of iron). Made by dissolving ferric hydroxide 

 in hypophosphorous acid, and evaporating. It is a grayish- white 

 powder, slightly soluble in water, soluble in hydrochloric acid, in 

 hypophosphorous acid, and in a warm, concentrated solution of an 

 alkali citrate. 



26. MANGANESE CHKOMIUM COBALT NICKEL. 



Manganese, Mn = 54.8. Manganese is found either as dioxide 

 (Black oxide of manganese, pyrolusite), MnO 2 , or as sesquioxide, 

 Mn 2 O 3 . In small quantities it is a constituent of many minerals. 



Metallic manganese resembles iron in its physical and chemical 

 properties, and may be obtained by reducing the carbonate with 

 charcoal. Manganese is darker in color than iron, considerably 

 harder, and somewhat more easily oxidized. 



Oxides of manganese. Four well-defined compounds of man- 

 ganese with oxygen are known in the separate state, and two others 

 only in combination with other elements. These oxides are : 



Manganous oxide (monoxide or protoxide), MnO. 



Manganous manganic oxide, MnO Mn 2 O 3 Mn 3 O 4 . 



Manganic oxide (sesquioxide), Mn 2 O 3 . 



Manganese dioxide (binoxide, peroxide, black oxide), MnO 2 . 



Manganic acid, 1 Not known in a separat e state, { ** + ^nO,. 

 Permanganic acid, > . H 2 O -f- Mn 2 O 7 . 



QUESTIONS. 241. Which metals belong to the "iron group/' and what are 

 their general properties ? 242. How is iron found in nature, and what com- 

 pounds are used in its manufacture? 243. Describe the process for manufac- 

 turing iron on a large scale, and state the difference between cast-iron, 

 wrought-iron, steel, and reduced iron. 244. State the composition and mode 

 of preparation of ferrous and ferric hydroxides. What are their properties? 

 245. Describe in words and chemical symbols the process for making ferric 

 chloride. What is tincture of chloride of iron ? 246. How are ferrous iodide 

 and bromide made? 247. State the properties of ferrous sulphate. Under 

 what other names is it known, and how is it made? 248. What change takes 

 place when soluble carbonates are added to soluble ferrous and ferric salts? 

 249. Mention agents by which ferrous compounds may be converted into ferric 

 compounds, and these into ferrous compounds. Explain the chemical changes 

 taking place. 250. Mention tests for ferrous and ferric compounds. 



