224 SCIENCE OF COMMON THINGS. 



"What is fuel carbon charcoal soot ? 



their decomposition, designated under the various names 

 of wood, peat, and coal. 



1401 What are the constituents of wood? 



Carbon, hydrogen, and oxygen, combined together, 

 make up the chief part of its bulk ; all wood also con- 

 tains water. 



1403 What is hydrogen? 



It is an inflammable gas, one of the elements of which 

 water is composed. The gas used in our streets is in 

 great part hydrogen. Hydrogen, when pure, has neither 

 taste nor odor. 



1403 What are the peculiar characteristics of hydrogen gast 



1. It is the lightest of all known substances ; 



2. It will burn immediately on being ignited ; and 



3. A lighted candle (immersed in this gas) will be 

 instantly extinguished. 



1404 What is carbon f 



A solid elementary substance, generally of a dark or 

 black color, well known under the forms of charcoal, 

 lampblack, coke, etc. 



1405 What is charcoal? 



"Wood which has been exposed to heat until it has 

 been deprived of all its gases and volatile parts. 



1406 Can all animal and vegetable substances, by partial burning, be 

 converted into coal f 



They can. 



1407* In the charring of animal and vegetable substances, do we gene- 

 rate charcoal, or did it exist there before % 



The carbon or coal existed there previously, though 

 in chemical combination with other bodies, which are 

 principally driven off by heat, as is apparent from the 

 fact that a charred body weighs much less than the 

 original substance ; animal and vegetable substances 

 consist, therefore, in part of coal. 



1408 Wliatissoot? 



Coal in a state of minute division, which is deposited 

 from the flame of bituminous or pit-coal, wood, oil, 



