108 AGRICULTURAL CHEMISTRY 



CO 2 . Observe the result. Add 5 cc. water to the cylinder in which 

 the splinter was placed, and then a little lime water; shake, and 

 observe the result. 



Questions, (i) Write the reaction for the preparation of CO 2 . 

 (2) What is a carbonate? (3) Is CaCO 3 soluble in pure water? 

 (4) Is it soluble in water containing CO 2 ? (5) What caused the 

 precipitate to form when the CO 2 gas was passed through the lime 

 water? (6) What is this precipitate? Write the reaction. (7) 

 What caused this precipitate to disappear when more gas was 

 passed through the solution? (8) What caused it to reappear 

 when the solution was boiled? (9) What caused the candle to be 

 extinguished when a receiver of CO 2 was poured over the flame ? 

 (10) O is a supporter of combustion ; CO 2 contains O ; why does 

 CO 2 not support combustion? (n) Is CO 2 a heavy or a light gas, 

 and what tests indicate that it is heavy or light? (12) What other 

 carbonate could be used for making CO 2 ? (13) What other acid 

 could be used for making CO 2 ? 



128. Carbon Monoxid. Carbon monoxid is formed 

 when carbon is only partially oxidized because of an in- 

 sufficient supply of air. In a coal stove, for example, 

 there is not a perfect supply of air in the interior of the 

 burning mass ; carbon monoxid is formed there and passes 

 to the surface where it burns as a blue flame. If the 

 draft is imperfect, a large amount of carbon monoxid is 

 formed. When a coal stove gives off gas, the carbon 

 monoxid is not oxidized, but is thrown off into the room. 

 Carbon monoxid is a light, colorless, combustible, poison- 

 ous gas, and can be produced by subjecting highly heated 

 carbon to the action of steam. The reaction is 

 C -f H 2 O = CO + 2H. Both CO and H are combustible, 

 and when they are enriched by some of the hydrocarbons, 

 so as to introduce materials for producing light, when 

 burned, they may be used for illuminating purposes, and 



