Also
[35]
where
- = specific volume of saturated steam (volume of 1 lb.) at a given temperature, , Pressure
- , = specific volume of air at the same pressure and temperature
- = density of saturated steam in lb. per cu. ft. at temperature
But we have for air
[36]
Therefore
[37]
Hence, substituting in [34]
[38]
- in. mercury = lb. per sq. ft.
Hence
[39]