MANGANESE. 153 



QUESTIONS. 



241. Which metals belong to the " iron group," and what are their 

 general properties ? 



242. How is iron found in nature, and what compounds are used in 

 its manufacture? 



243. Describe the process for manufacturing iron on a large scale, 

 and state the difference between cast-iron, wrought-iron, steel, and re- 

 duced iron. 



244. State the composition and mode of preparation of ferrous and 

 ferric hydrates. 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. What is the composition of ferrous phosphate, and what is the 

 phosphate of iron, U. S. P. ? 



250. Mention tests for ferrous and ferric compounds. 



26. MANGANESE CHROMIUM COBALT NICKEL. 



Manganese, Mn = 54. Manganese is found either as dioxide 

 (black oxide of manganese, or pyrolusite), Mn0 2 , or as sesqui- 

 oxide, Mn 2 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 : 



Manganese 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 H..O MnO,. 



< >. ot known in a separate state } 2 

 Permanganic acid, I J H.,0 -f- Mn 2 O 7 . 



