FUELS AND CARBON COMPOUNDS 



267 



FIG. 232. Electric Grill. 



hot-water bags, and numerous other appliances which 

 utilize a small amount of current to apply heat exactly 

 where it is needed (Figures 231, 232, 233). 



Carbon Dioxide. Car- 

 bon dioxide is occasionally 

 found issuing froni the 

 ground, especially in vol- 

 canic regions, and dis- 

 solved in the water of 

 certain springs. The 

 charged water of the soda 

 fountains is simply water 

 in which a large amount of 

 carbon dioxide has been 

 dissolved under pressure. Carbon dioxide is always 

 formed when carbon or carbon compounds burn in air 

 or oxygen. A small amount of carbon dioxide is always 



present in the air, since it 

 is produced when any sub- 

 stance is burned, by the 

 decay of all vegetable and 

 animal matter, and by the 

 breathing of plants and ani- 

 mals. 



Preparation of Carbon 

 Dioxide. Place a few 

 pieces of marble or lime- 

 stone in a bottle (Figure 

 234) and pour over them 

 a dilute solution of hydrochloric acid. The gas formed 

 is carbon dioxide. The gas may be collected by down- 

 ward displacement of air, or over water as we collected 

 oxygen. 



FIG. 233. Electric Toaster. 



