452 Introduction to the Study of Science 



producing region ranks first in importance? What kind of ores does 

 it produce? 



11. Describe how iron ores are mined. 12. Compare the formation 

 of iron ore with that of sandrock and limerock. 13. What was the 

 origin of the iron ores of the Lake Superior region ? 14. Describe the 

 bodies in the Birmingham region. 15. How have the brown ores 

 been formed? 



16. Describe a blast furnace. 17. Why do iron-producing firms 

 employ chemists? 18. How is the oxygen removed from the ore in 

 the blast furnace? 19. How are impurities like silica removed? 

 20. How is the molten iron from the blast prepared for commerce? 

 What is it called? 21. What uses are made of slag? 22. Why is the 

 dust from the smelter saved? The gas? 23. What are the charac- 

 teristics of pig iron? 24. What direct use is made of pig iron? 

 25. How does malleable cast iron differ from ordinary castings? 



26. What change takes place in the composition of pig iron when 

 it is converted into steel? 27. What proportion of pig iron is con- 

 verted into steel ? 28. Name the processes by which steel is made 

 from pig iron. 29. Describe the construction and operation of a 

 Bessemer converter. 30. (a) What two objectionable elements does 

 the Bessemer converter fail to remove entirely from the pig iron? 

 (6) What effect has each of these impurities on the character of the 

 steel? 31. Why does the open-hearth process yield a higher grade 

 of steel than the Bessemer process? 32. (a) What is the duplex 

 process? (6) What are its advantages? 33. What process is used 

 for tool steel? 34. What is the source of carbon in the cementation 

 and crucible process ? 35. (a) What is the most recent process of 

 making steel ? (6) What quality of steel does it produce ? (c) What 

 are its advantages in comparison with other processes? 36. What is 

 steel? 37. How is its hardness dependent on the proportion of car- 

 bon it contains? 



38. (a) What is the purpose of tempering steel? (6) Describe the 

 process. 39. What does a blacksmith use as an indicator of tem- 

 perature? 40. Why are steel tools and instruments polished? 

 41. Mention several uses of steel. 



42. What percentage of pig iron is converted into wrought iron ? 

 For what purpose is it used? 43. Compare wrought iron a'tid soft 

 steel. 44. What are the useful properties of wrought iron? 

 45. (a) How is wrought iron made? (6) What is the " bloom " ? The 

 "puddle bar"? The "merchant bar"? (c) What is the charac- 

 teristic structure of the " merchant bar "? (d) How is the structure 

 produced ? 



