CARBONIC OXIDE. 195 



acid, and is one source of the danger which arises from 

 open fires in close rooms. One-two-hundredth of it 

 makes the air, if inhaled for any considerable time, a 

 fatal poison. 



479. COMBUSTION OF CARBONIC OXIDE. 



How is car- 



ionic oxide For small experiments, the gas is best pre- 



best prepared? ^^ by coyermg ft half tea -spOOnful of 



oxalic acid* with oil of vitriol, and heating them to- 

 gether in a test-tube. The gas, on 

 being kindled at the mouth of the 

 tube, burns with a beautiful blue 

 flame. The experiment is re-ndered 

 more striking, by producing a jet, as 

 represented in the figure. The gas 

 thus obtained is really a mixture of 

 carbonic oxide with carbonic acid, 

 but the admixture does not mate- 

 rially affect the experiment. 



480. EXPLANATION. Each molecule of 



Explain the . 



formation of oxalic acid contains carbon, oxygen, and 

 carbonic oxide. hydrogerij in the proportion to form one 



molecule each, of water, carbonic oxide, and carbonic 

 acid. Through the agency of sulphuric acid, this de- 

 composition is accomplished. The water remains with 

 the acid while the gases are evolved. 



481. IT PRODUCES METALS FROM OXIDES. 



effect on me- With the help of a high temperature, car- 

 talhc oxides? bon j c ox [^ e takes oxygen from oxides, 



and converts them into metals. It contains oxygen 



* This acid has the appearance of a salt, and is poisonous. 



