90 



CHEMISTRY. 



When, however, it emerges into the air, if the heat be suffi- 

 cient to inflame it, it takes from the air an additional quan- 

 tity of oxygen, and thus becomes carbonic anhydride. 

 When the whole body of the coal has become thoroughly 

 ignited, there is no more carbonic oxide formed, but only 

 carbonic anhydride, and hence there is no longer any flame. 

 When charcoal burns without a good supply of air, carbonic 

 oxide is produced, mingled with carbonic anhydride. This 

 gas is very poisonous, much more so than the carbonic an- 

 hydride. It is the mixture of the two gases that produces 

 such injurious effects when charcoal is burned in a chafing- 

 dish or an open furnace in a close room. We have known 

 similar effects produced when a damper of an anthracite coal- 

 stove was closed before the coal was well ignited, thus pre- 

 venting the carbonic oxide as it rises from being fully con- 

 verted into carbonic anhydride, and forcing some of both 

 of these gases out into the room. 



113. Preparation of Carbonic Oxide. This gas is common- 

 ly obtained from oxalic acid, the acid which gives the sour 

 taste to sorrel. This is composed of carbon, oxygen, and hy- 

 drogen, the same ingredients which we have in carbonic an- 

 hydride and 

 carbonic ox- 

 idephts water, 

 but in differ- 

 ent propor- 

 tions. The 

 chemist by 

 means of sul- 

 phuric acid 

 splits up, as 

 we may say, 

 the oxalic acid 

 into these two 



