422 



ACCOUNT OF THE ARCTIC REGIONS 



the surplus must be deposited. By the help of the 

 following Table, derived from measurements of the 

 curve representing the dissolving power of the air, 

 this subject may be more familiarly illustrated *. 



Now, a mass of air at temperature zero, can sup- 

 port, it appears, about one three hundred and sixty- 

 fifth part of its weight of moisture ; or a mass of 

 air 365 lb. in weight, can contain, when saturated 

 at temperatiu-e 0°, 1 lb. of water ; at temperature 



" This Table, though very nearly correct, is yet but an 

 approximation. It, however, serves every purpose of illus- 

 tration. What is here called the dissolving power of the 

 air, is perhaps, correctly speaking, the dissolving power 

 of caloric, the water itself that is evaporated being con- 

 verted into an elastic vapour, by its combination with the 

 matter of heat. This vapour forms a part of the air of the at- 

 mosphere. Decrease of atmospheric pressure and increase of 

 lemperature. accelerate its ftn-mation. 



