QUESTIONS. 331 



pyrites ? In what different forms is native gold found ? What is 

 said of some of its localities ? 



47. What is said of the amount of gold obtained from Australia and 

 the United States ? What of the modes of obtaining gold ? What 

 of the sorting of gold by natural operations ? Explain the operation 

 by which a ' ' pocket" of gold is formed. 



48. Describe the manner of effecting a large "washing" in the 

 search for gold. What are the quantities of gold that make it so use- 

 ful ? What is said of gilding ? What of the alloys of gold ? With 

 what is platinum generally found associated ? What are its proper- 

 ties? 



49. What is said of the metals found in company with platinum ? 



CHAPTER VI. 



49. What are oxy-salts ? What are haloid salts, and why are they 

 so called? 



50. What is saltpetre ? What is said of its production in nature 

 in different localities ? Of what use is it in the composition of gun- 

 powder? What is said of the nitrate of soda? What is the compo- 

 sition of common salt ? What is said of its diffusion in the earth ? 

 Under what circumstances is water in seas or lakes exceedingly salt ? 

 Where are there famous salt mines ? What is said of the mines of 

 Cracow ? Where are there hills of salt ? How is salt obtained in 

 this country ? 



51. What is the composition of borax? What is said of the most 

 noted locality of it? Under what circumstances is boracic acid 

 evolved ? What are the different forms of carbonate of lime ? What 

 is said of its diffusion in the earth ? How is it distinguished from oth- 

 er minerals that resemble it? What effect does heat produce upon 

 it ? What is hydraulic lime ? 



52. What is marl? What calcareous tufa? What fact is stated 

 about chalk ? To what is the name calcareous spar applied ? What 

 is said of some of its varieties ? 



53. What is oolitic marble ? Explain the formation of stalactites 

 and stalagmites. What is said of Weyer's Cave ? What of the mag- 

 nesian carbonate of lime? 



54. State in full what is said of fluor spar. What is said of apa- 

 tite ? What of the salts of magnesia ? 



55. What is said of the chlorid of ammonium ? What is the com- 

 position of common alum ? What is said of other alums? What of 

 the feather alum ? What of the phosphates of alumina ? 



