CHEMICAL ACTION. 33 



>ing your hand into the mixture first, 

 and into snow afterwards, the mere snow 

 will seem to be comparatively warm. 



Q. What is yiKvt 



A. Combustion is another instance of 

 heat, arising from chemical action. 



Q. What two things are essential to produce 

 combustion ? 



A. Fuel and air. 



Q. What are the elements of fuel ? 



A. As bread is a compound of flour, 

 yeast, and salt; so fuel is a compound of 

 hydrogen and carbon. 



Q. What are the ELEMENTS of atmospheric AIR ? 



A. The air is a compound of oxygen 

 and nitrogen mixed together; in the 

 proportion of five gallons of nitrogen, to 

 one of oxygen. 



Q. What is CARBON ? 



A. The solid part of fuel. It abounds 

 also in all animal bodies, earths, and 

 minerals. 



Q. Mention some different SPECIES of CARBON. 



A. Common charcoal, lamp-black, 

 coke, black lead, and the diamond, are 

 all varieties of carbon. 



