THE WATER OF THE AIK 



23 



per cubic foot. Thus, when a cubic foot of space contains, 

 besides the air, 7 grains (absolute humidity) of water vapor, 

 and is able to contain at that temperature 14 grains (satura- 

 tion) of water vapor, it has 50 per cent (relative humidity) of 

 all that it is able to contain. 



The following table shows the amount of water per cubic 

 foot of space which is present at saturation at the different 

 temperatures given. The temperatures stated are Fahrenheit, 

 and the amount of water is given in grains per cubic foot. 



Grains per cu. ft. 



20 F 1.235 60' 



22 F 1.355 62' 



24 F. ..... 1.483 64' 



26 F 1.623 66' 



28 F 1.773 68< 



30 F: . . . . . 1.935 70' 



32 F 2.113 72' 



34 F 2.279 74' 



36 F 2.457 76' 



38 F 2.646 78 ( 



40 F 2.849 80 ( 



42 F 3.064 82' 



44 F 3.294 84< 



46 F 3.539 86 ( 



48 F 3.800 88< 



50 F 4.076 90< 



52 F 4.372 92' 



54 F 4.685 94' 



56 F 5.016 9G C 



58 F. 5.370 98' 



Grains per cu. ft. 



F 5.745 



F 6.142 



F 6.563 



F. ..... 7.009 



F 7.480 



F 7.980 



F 8.505 



F 9.066 



F. ..... 9.655 



F 10.277 



F 10.934 



F. ..... 11.626 



F 12.356 



F 13.127 



F 13.937 



F 14.790 



F 15.689 



F 16.634 



F 17.626 



F. . 18.671 



23. Some examples. If the temperature falls below that 

 at which the contained vapor saturates the space, some of the 

 water will condense into the liquid form. For instance, if the 

 space in a room is at a temperature of 70 F. and contains 3.8 

 grains of water vapor to the cubic foot, the air will appear 

 rather dry, for it would be able to contain over 4 grains 

 more without being saturated (see table in section 22). If, 



