VENTILATION 171 



VENTILATION 



Results of Burning. Most gases contain carbon, carbon monox- 

 ide, and a gas called hydrogen. We have learned that oxygen 

 unites with substances to form oxides during the process of com- 

 bustion. Carbon unites with oxygen to form carbon dioxide. 

 Carbon monoxide unites with oxygen to form carbon dioxide. 

 Hydrogen unites with oxygen to form hydrogen oxide (water) 

 (H 2 0). 



Symbols or formulas are used to express these compounds. 

 C stands for carbon, for oxygen, and because two parts of oxygen 

 unite with one part of carbon the formula for carbon dioxide is CCb. 

 Carbon monoxide would be expressed by CO. More oxygen can 

 unite with this compound; therefore, it can burn. When oxygen 

 can no longer unite with the compound, that is, when it has all the 

 oxygen it can hold, it can no longer oxidize, and hence can no longer 

 burn. The same is true of hydrogen, a gas we shall study about 

 in the chapter upon water. 



Carbon Dioxide (CO2). Carbon dioxide will be seen to be the 

 chief product of combustion. We have already learned that this 

 gas is useful in extinguishing fire. It is also used for soda water. 

 Large quantities of the gas are forced into pure water in tanks. 

 These tanks are attached to the soda water fountain, and the 

 carbonated water is drawn off into glasses, flavored with chocolate, 

 vanilla, etc., and sold to the customers. Water containing large 

 amounts of carbon dioxide is called carbonic acid. 



Sources of Carbon Dioxide (CO2). Every chimney is giving 

 out large quantities of C02 to the atmosphere. It was estimated at 

 one time that certain iron works sent into the atmosphere every 

 day more than five million pounds of carbon in the form of carbon 

 dioxide. The burning of gas, the burning of wood, and the exhaling 

 of air by human beings and animals give to the air large quantities 

 of carbon dioxide. 



A single adult will give off nearly 2 pounds of carbon dioxide 

 every day, or about 22 cubic feet. That is, the normal person 

 breathes out about .9 cubic foot each hour. 



The amount of air in the average person's lungs is from 210 to 



