HENRY'S LAW 247 



instance, the pressure of the gas be doubled, twice as much of it 

 will go into solution. The appended table contains experimental 

 verifications of this Law of Henry. 



TABLE XXXV. 



SOLUBILITY OF CO, IN WATER AT 15 C. 

 p. v. V./P. 



69-8 0-94 0-0135 



128-9 1-86 0-0144 



200-2 2-90 0-0145 



311-0 4-5 0-0145 



where P = pressure in mm. of Hg. of C0 2 , 



v = volume of C0 2 (measured at N.T.P.) absorbed by 1 c.c. of water 

 at 15 C. 



(The same volume of gas at constant temperature is absorbed 

 by the fluid, no matter what the pressure is. Increase of pressure 

 proportionally increases the weight of unit volume. Thus, if one 

 volume of water dissolves one volume of gas weighing 1 gram at 

 1 atmosphere pressure, then, if the pressure be raised to two 

 atmospheres, 1 volume of water would dissolve 1 volume of the 

 gas weighing 2 grams, or if reduced to normal pressure, 1 volume 

 of water would dissolve 2 volumes of the gas weighing 2 grams.) 



Absorption coefficient (usually denoted by the Greek letter a). 



Different gases, just like different solids, vary in their solu- 

 bilities. The volume of gas (at N.T.P.) which dissolves in 1 c.c. 

 of water under a pressure of one atmosphere is termed its absorp- 

 tion coefficient, e.g. 1 c.c. of water will dissolve at N.T.P. 0-0489 c.c. 

 of oxygen, 0-0239 c.c. of nitrogen, and 1 -713 c.c. of carbon dioxide. 

 The volume of gas absorbed by 1 c.c. of water under any pressure 

 may be found by the following equation : 



L=ap, 



where L=amount of gas dissolved, 

 a = absorption coefficient, 

 p=pressure in atmospheres. 

 Increase of temperature causes the solubility of gases to decrease. 



TABLE XXXVI. 



ABSORPTION COEFFICIENTS AT VARIOUS TEMPERATURES. 



Temperature. Oxygen. Nitrogen. Carbon-dioxide. 



0C. 0-0489 0-0239 1-713 



10 C. 0-0380 0-0196 1-194 



20 C. 0-0310 0-0164 0-878 



30 C. 0-0262 0-0138 0-665 



40 C. 0-0231 0-0118 0-530 



