328 QUESTIONS. 



talline forms ? Under what circumstances do they do this ? What 

 is said of forming crystals by deposit from solution ? 



18. Explain the formation of frost and dew. Give examples of 

 the conversion of liquids and gases into crystals. What is said of the 

 production of crystals by the influence of heat ? What of the water 

 of crystallization ? What is an amorphous mineral ? What a di- 

 morphous mineral? 



19. What is said of the arrangement of crystals? What of the 

 crystals of common salt? What arrangements are there in rocks 

 that are somewhat like crystallization ? What is cleavage ? What 

 are some of its different modes ? 



20. What is said of cleavage in quartz? What are primary forms ? 

 How many are there? Into how many classes are they divided? 

 What are the crystals of the first class ? What is a rhomb ? What 

 an octahedron ? What a dodecahedron ? 



21. Show how the cube may be converted into the octahedron by 

 cleavage. Show how the octahedron can be converted into the cube. 

 What are secondary forms? In what two ways are they produced 

 in nature ? Illustrate the mode by addition. 



22. What is said of constancy in the forms of crystals ? What of 

 symmetry ? 



22. Illustrate the analogy between the symmetry of the mineral 

 and that of the living world. 



CHAPTER III. 



23. What are the four grand elements of which animal and vege- 

 table substances are composed ? What is said of the diffusion of car- 

 bon ? What constitutes the diamond ? 



24. How can the diamond be proved to be pure carbon ? How 

 does it differ from charcoal and anthracite ? What is said of the col- 

 oring of diamonds? What are the qualities of diamonds? What is 

 said of their size ? What are the meaning and origin of the word 

 carat ? 



25. What is said of the cost of diamonds ? What of the art of cut- 

 ting them ? What of the expense of the process ? What of the uses 

 of the diamond ? 



26. What are the chief localities in which diamonds are found? 

 What is said of the modes of collecting them ? What is the compo- 

 sition of graphite ? What are its properties ? What its uses ? How 

 is it prepared for use in pencils? What is the difference in com- 

 position between bituminous and non-bituminous coal ? What gas is 

 produced from bituminous coal ? 



27. What is the blue flame of imperfectly burning anthracite ? How 



