SCIENTIFIC READINGS. 115 



97- Why is the top of the wick in common candles 

 black when burning ? 



98. What angle of inclination must a candle have so 

 as not to require snuffing ": 



99. What is Sir Richard Phillips's theory of Combus- 

 tion ? 



100. Define Inflammation, Ignition, and Detonation or 

 Explosion. 



LIGHT. 



101. What is Light? 



102. What is the effect of the action of light on vege- 

 tables ? 



103. W T hy are the hearts of lettuces and other vegeta- 

 bles white, as also the bellies of fishes, and the inner 

 feathers of birds, &c. } 



104. What was the opinion of Sir Isaac Newton in 

 regard to the nature of light ? 



105. What effect has the sun's rays when condensed 

 and thrown on a delicate balance ? 



106. In what direction do the rays of light proceed ? 



107. Which rays of light from the sun that fall on 

 our atmosphere undergo refraction, those that fall per- 

 pendicularly, or those that fall obliquely ? 



108. Required the velocity of light. 



109. Through what cause is it that the heavenly bodies 

 appear higher in the heavens than they actually are ? 



1 10. What is meant by a diaphanous body ? 



111. On what does the science of dioptrics depend? 



112. When a ray of light passes from a dense into a 

 rarer medium, how, or in what direction is it refracted ? 



113. In what direction is a ray of light refracted, when 

 it passes from a rare into a denser medium ? 



114. When a ray of light falls upon a body and it does 

 not become absorbed, what is the result ? 



115. What kind of bodies reflect light most ? 



116. On what does the quantity of reflected light de- 

 pend ? 



117. To what is the angle of reflection always equal : 



118. Which colour absorbs, and which reflects light 

 the most ? 



