ARSENIC, ANTIMONY, BISMUTH. COPPER AND LEAD. 253 



QUESTIONS. 



335. Give the names and formulae of the oxides of manganese. Which 

 ones form salts? 336. What are the properties of pure iron? 337. What 

 is said of the abundance and importance of iron ? 338. What oxides does 

 iron form ? What is said of ferrous hydrate ? Mention some of the ores 

 of the monoxide of iron. Of the sesquioxide. Of ferric hydrate. How 

 many grammes of water are there in 100 grammes of ferric hydrate ? How 

 many grammes of oxygen ? How many gallons of oxygen in one pound 

 of rust ? What is the composition of the so-called magnetic oxide of iron ? 

 What are its properties ? 339. What are meteorites ? 340. Describe the 

 process of making pig-iron. Why is limestone added ? 341. What is said 

 of cast iron ? 342. What is the process of converting cast iron into wrought 

 iron? Describe the change in properties thus produced. Why can 

 wrought iron be welded ? 343. In what does steel differ from iron ? 

 What are its properties ? What is annealing ? 344. In what does the 

 Bessemer process consist? 345. What is said of tempering steel? What 

 colors does it assume? 346. Name and describe the principal sulphide of 

 iron. Of what use is it ? 347. Name some other salts of iron. 348. 

 What is the nature of cobalt ? Whence its name ? 349. What is said of 

 sympathetic ink? 3.">0. What are the properties of nickel? 351. Name 

 some of its salts. 352. What are the most important oxides of chromium ? 

 What is said of the chromates? 353. What are the uses of tin ? How are 

 pins made ? What is moirt metalllgue * What peculiar property has a 

 bar of tin ? 354. What is known as " tin-salts ?" How used ? 355. What 

 is mosaic gold ? How made ? How is the monosulphide obtained ? 



CHAPTER XIX. 



GROUP VII. ARSENIC, ANTIMONY, AND BISMUTU. GROUP VIII. 



COPPER AND LEAD. 



356. Arsenic. What is known as arsenic in common lan- 

 guage is a compound of this metal with oxygen, called by 

 the chemist arsenious anhydride, As 2 O 3 . This arseniotis 

 anhydride is a deadly poison, so that " poisonous as arsenic" 

 is a common expression. It is used for the destruction of 



