44 



LIVING IN AN OCEAN OF AIR 



National Geographic Society 



The start of the stratosphere flight above Rapid City, South Dakota. Do you 

 know the use of any of the instruments contained in the gondola under the balloon ? 



time and found it weighed more. He concluded this 

 greater weight must be due to the extra air in the ball. 



Our knowledge about what the air is dates back a little 

 more than a century, when Priestley, an Englishman, 

 separated oxygen out of the air, thus showing it to be a 

 mixture of gases. Then the Frenchman, Lavoisier, 1 dis- 

 covered that oxygen causes things to burn and an English- 

 man named Cavendish shortly after found that carbon 

 dioxide was a gas formed when things burned. Priestley 

 discovered the gas that made up almost four-fifths of the 

 atmosphere and Lavoisier named it nitrogen. Recently 

 small quantities of other gases have been found to be 

 a part of the air mixture. 



As discoveries in pure science are followed by applica- 

 tions of science useful to man, so the discovery that air 

 pressure could be measured by an instrument called the 

 1 Lavoisier (la'vwa'zya'). 



