AND AGRICULTURE. 



73 



Fig. 22. 



chalk, into a wine-glass, and pouring upon it a 

 portion of vinegar, or dilute muriatic acid. 

 That carbonic acid gas is liberated, you may 

 prove by bringing a lighted taper into contact 

 with it, when it will be extinguished. 



When limestone, or the carbonate of lime, is 

 burned in a kiln, the carbonic acid is driven off 

 by the heat, and the lime alone remains. It is 

 now called quick, caustic, or hot lime. A ton 

 of limestone yields about eleven and a quarter 

 hundred weight of quick-lime. 



If water is added 

 to quick-lime, it 

 rapidly absorbs, or 

 drinks it in, giving 

 out a great deal of 

 heat in the form of 

 steam, swelling up 

 largely, and at 

 length falls down 

 into a fine powder. It is now called slaked 



Questions. What is the effect of burning limestone in 

 a kiln? What is it called after burning? How much 

 quick-lime does a ton of limestone yield ? What is the effect 

 of adding water to quick -lime ? What is it called after thus 

 falling into powder ? 



7 



