76 HEAT. 



176. ABSORPTION NOT THE CAUSE. It 

 MM* allorp- is not uncommonly supposed that the air 

 tion is not, the acts to absorb vapor as a sponge does to 

 draw up water. The term " saturated" 

 used for convenience in scientific works is calculated 

 to give this impression. But vapor rises just as well, 

 and even more rapidly, into a vacuum, or space from 

 which all the air has been removed. 



WJiat then is 177. INCREASED DENSITY OF VAPOR THE 



the cause? CAUSE. The air absorbs any vapor that 

 may be formed, whether more or less dense. At higher 

 temperatures, denser vapor is produced. It follows that 

 the air will contain more water, in proportion to the 

 elevation of its temperature. 



178. REMOVAL OF AIR DOES NOT IN- 



Does the remo- . 



val of air in- CREASE THE QUANTITY. It might be SUD- 



"formation *o/ P ose( ^ tnat more water would rise into a 

 vapor ? vacuum in the form of vapor, than into a 



space filled with air, on the ground that the removal 

 of the air would make more room for something else. 

 But this is not the fact. The presence or absence of 

 air makes no difference. 



179. SEVERAL GASES AND VAPORS MAY 



Do vapors and _ ., 1 , ,, 



gases exclude OCCUPY THE SAME SPACE. It follows from 



each other ? the lagt p ara g rap h t h at vap ors do not dis- 

 place the air ; they penetrate it instead. And it is a 

 remarkable fact, that a number of vapors may occupy 

 the same space without interfering with one another ; 

 and each in the same quantity as if the rest were ab- 

 sent. 



