EXPANSION OF GASES. II 



imperfectly propagated downwards. The surface in the end 

 freezes, and the ice may thicken, but at the depth of a few feet, 

 the temperature is not under 40, which is high when compared 

 with that frequently experienced, even in this climate, during 

 winter. 



If water continued to become heavier, until it arrived at the 

 freezing temperature, the whole of it would be cooled to that 

 point before ice began to be formed; and the consequence 

 would be, that the whole body of water would rapidly be 

 converted into ice, to the destruction of every being that 

 inhabits it. Our warmest summers would make but little 

 impression upon such masses of ice ; and the cheerful climate, 

 which we at present enjoy, would be less comfortable than the 

 frozen regions of the pole. Upon such delicate and beautiful 

 adjustments, do the order and harmony of the universe 

 depend. 



Expansion of Gases. The expansion by heat in the different 

 forms of matter is exceedingly various. 



By being heated from 32 to 212, 



1000 cubic inches of iron become 1004. 

 1000 water 1045. 



1000 air 1375. 



Gases are, therefore, more expansible by heat than matter 

 in the other two conditions of liquid and solid. The reason 

 is, that the particles of air or gas, far from being under 

 the influence of cohesive attraction, like solids or liquids, are 

 actuated by a powerful repulsion for each other. The addition 

 of heat mightily enhances this repulsive tendency, and causes 

 great dilatation. 



The rate of the expansion of air and gases from increase of 

 temperature, was involved in considerable uncertainty till a 

 recent period. This arose from the neglect of the early experi- 

 menters to dry the air or gas upon which they operated. The 

 presence of a little water by rising in the state of steam into the 

 gas, on the application of heat, occasioned great and irregular 

 expansions. But in 1801, the law of the dilatation of gases 

 was discovered by M. Guy-Lussac, of Paris, and by our coun- 

 tryman, Dr. Dalton, independently of each other. By keeping 

 the gases experimented upon dry, these philosophers were en- 

 abled to discover that all gases experience the same increase in 

 volume by the application of the same degree of heat. 



