SCIENTIFIC READINGS. 113 



55. Describe Buffon's combination of plane mirrors, 

 and the effect produced ? 



56. What was the effect produced by Mr. Parker's 

 burning-glass : 



57. What are the various means by which caloric is 

 produced ? 



58. How is caloric produced by combustion ? 



59. By what means is the strongest heat produced by 

 combustion ? 



60. How is heat produced by Percussion; how by 

 Friction ? 



61. Explain how fire is produced by the collison of 

 the flint and steel ? 



62. To what does oxygen owe its gaseous state ? 



63. How do savages procure fire? 



64. What is the general rule for the production of 

 heat by chemical mixture ? 



65. If two ounces of sulphuric acid be mixed with 

 eight ounces of cold water, what will be the quantity of 

 the mixture ? 



66. Why is heat evolved in slaking lime ? 



67- By what means has the strongest heat known been 

 produced ; and what has been the effect resulting there- 

 from ? 



68. With what force will steam, at 590, press on a 

 space of two inches square, of three inches, and of four 

 inches square ? 



69. If a mirror of four feet in diameter produce a focus 

 of half an inch in diameter, in what ratio will the heat be 

 increased ? 



70. If a convex lens of one foot in diameter produce 

 a focus of a quarter of an inch in diameter, in what ratio 

 will the sun's rays be condensed ? 



COMBUSTION. 



71. Define Combustion. 



Which are simple, and which compound combus- 

 tibles ? 



