336 



AGRICULTURAL ANALYSIS 



ture is subjected, is partly neutralized by the tension of the water 

 vapor. The real pressure to which the gas, whose volume is to 

 be determined, is subjected is, therefore, diminished by that ten- 

 sion. If, for instance, a gas in contact with water show a vol- 

 ume of 35 cubic centimeters at 22 and 740 millimeters baromet- 

 ric pressure, its volume is really greater than if it were perfectly 

 dry. How much greater can be determined by inspecting the 

 table; for at 22 the tension of water vapor is 19.675 millime- 

 ters of mercury. The real pressure to which the volume of gas 

 is subjected is, therefore, 740 19.675=720.325 millimeters. 



If, therefore, in the example given, the nitrogen were in con- 

 tact with water, the calculation would proceed as follows: 

 32-18 X 7 2Q.325 _ 



V = 

 And 30.5X1.25456=38-26. 



760 



Millimeters tension of aqueous vapor for KOH solutions of 



