1838.] Specific Gravities of Aqueous Vapour^ 8fc, 



127 



T— 32 30 



^ — - — _^ , volume at 32o 



480 30 -FT 



being unity, but by Gay Lussac's formula for the expansion of a gas on 



being saturated with moisture, the volume is 



B 



= V 



B— FT B being the barometric pressure, and 

 the whole expansion from heat and moisture should have been 



T— 32° \ / 30 



==U 480 ; • V 30-ft; 



In the table now given the specific gravity of dry air, is : — 



_ ___ 1 



~~i J T— 320 

 1 -{- 



480 



and the specific gravity of saturated air is 



1 



-= w {I + V T) (l + i; V) 

 The specific gravity of aqueous vapour is the same as given by 

 Daniel, it is entered here for the convenience of computing the specific 

 gravity of air, when not saturated, by the formula, as given by Galbraith, 



a= V'^ 30 ; V 448 -t- Dt; 



ff — the specific gravity of the air v/lien 

 D t= the dew point 



Q = the specific gravity of dry air ^ 



S z= the specific gravity of aqueous vapour > at the temp. T. 



ii^T'^ the tension of vapour 5 



T = the temperature of the air. 



By the same authority is given the subjoined formula for ttie speci. 

 fic gravity of saturated air, which, it may be shown, is the same aS 

 that from which this table has been computed. 



a. FT 

 ~ a -{-s- 



3Q 



