CARBONIC ACID. 267 



carbonic add gas, which readily combines 

 with lime, and produces "carbonate of 

 lime, 1 which is entirely free from all 

 offensive odour. 



Q. W hy do persons throw LIME into SEWERS 

 in summer time ? 



A. Sewers (like bins) contain large 

 quantities of carbonic acid, which readily 

 combines with lime, and produces car- 

 bonate of lime ; and thus the offensive 

 gas of the sewer is neutralized. 



Q. Can carbonic acid be removed in any way 



BESIDES by LIME ? 



A. Yes ; water thrown into a pit will 

 disperse the carbonic acid. 



Q. What effect has WATER on CARBONIC ACID 

 GAS? 



A. Water (under pressure) absorbs 

 carbonic acid gas; and parts with it 

 (when the pressure is removed} in the 



form of EFFERVESCENCE. 



Q. Why does AERATED WATER effervesce, 

 when the CORK is removed ? 



A. While the cork was fastened 

 down, the* water absorbed the carbonic 

 acid ; but the moment the pressure is 



Aa 2 



