THE KEASOK WHY 



* And the sirong shall be as tow, and the maker of it as a spark, and they shaL 

 both burn together, and none shall quench them." ISAIAH i. 



105. Wliy is there so little smoke tvhen the fire is red? 

 Because the hydrogen and the volatile parts of the coal have 



already been driven oft' and consumed, and the combustion that con- 

 tinues is principally caused by the carbon of the coals, and the 

 oxygen of the air. 



106. Will carl/on, burnt in oxygen, produce flame and 

 smoke ? 



It burns brightly, but it produces neither flame nor smoke. 



107. Why do not charcoal and coke fires givefiamc ? 

 Because the hydrogen has been driven off by the processes by 



which charcoal and coke are made. 



108. What is a conductor of heat? 



A conductor of heat is any substance through which heat is 

 readily transmitted. 



109. Wliat is a non-conductor of heat? 



A non-conductor is any substance through which heat will not 

 pass readily. 



110. Name a few good conductors. 



Gold, silver, copper, platinum, iron, zinc, tin, stone, and all dense 

 solid bodies. 



111. Name a few non-conductors. 



Fur, wool, down, wood, cotton, paper, and all substances of a 

 spongy or porous texture. 



112. IToio is heat transmitted from one lody to another ? 

 By Conduction, Radiation, Reflection, Absorption and Convection. 



113. What is the Conduction of heat ? 



It is the communication of heat from one body to another by con* 

 tact. If I lay a penny piece upon the hob, it becomes hot by 

 conduction- 



114. What is the Eadiaticn of heat? 



The transmission of heat by a series of rays. If I hold ray hand 



