BURNING OR OXIDATION 



gling liquids interact and liberate carbon dioxide. A part of 

 the gas thus liberated dissolves in the 

 water of the soda solution and escapes 

 from the tube with the outflowing 

 liquid, while a portion remains undis- 

 solved and escapes as a stream of gas. 

 The fire extinguisher is therefore the 

 source of a liquid containing the fire- 

 extinguishing substance and further 

 the source of a stream of carbon diox- 

 ide gas. 



51. Carbon. Although carbon di- 

 oxide is very injurious to health, both 

 of the substances of which it is com- 

 posed are necessary to life. We our- 

 selves, our bones and flesh in partic- 

 ular, are partly carbon, and every 

 animal, no matter how small or insig- 

 nificant, contains some carbon ; while 

 the plants around us, the trees, the 

 grass, the flowers, contain a by no 

 means meager quantity of carbon. 



Carbon plays an important and va- 

 ried role in our life, and, in some one of its many forms, 

 enters into the composition of most of the substances which 

 are of service and value to man. The food we eat, the 

 clothes we wear, the wood and coal we burn, the marble we 

 employ in building, the indispensable soap, and the orna- 

 mental diamond, all contain carbon in some form. 



52. Charcoal. One of the most valuable forms of carbon 

 is charcoal ; valuable not in the sense that it costs hundreds 

 of dollars, but in the more vital sense, that its use adds to 

 the cleanliness, comfort, and health of man. 



FlG. 25. Inside view of a 

 fire extinguisher. 



