Liquid Solutions 17 



the beginning of such a process of mixing, however, a defi- 

 nite diffusion tension exists and can be demonstrated — a dif- 

 fusion tension produced on the one hand by the solute, and 

 on the other by the solvent. These diffusion tensions are 

 identical in their nature with those spoken of in the last 

 chapter. They increase in amount with rise in temperature, 

 and, in case there are several solutes, each one has its own 

 diffusion tension. These facts are found to be fundamental 

 in the consideration of osmotic pressure. 



Above any liquid mixture contained in a closed jar which 

 it does not fill, there will be a gas mixture of the vapors 

 of the solvent and of the several solutes. Each body will 

 have its own vapor pressure, and the total pressure of the 

 gas mixture will be the sum of its partial pressures. 



II. SOLUTIONS OF GASES IN LIQUIDS 



Gas solutes behave in the same manner as that just de- 

 scribed for liquid solutes. The amount of gas going into 

 solution, when a mass of it is brought into contact with a 

 mass of liquid solvent, increases with the temperature and 

 pressure. Diffusion pressures of solvent and solute are 

 developed here also, and are constant for a given tempera- 

 ture; they also vary with the absolute temperature. There 

 may be several gaseous solutes in the same solution, and in 

 this case each develops its own diffusion tension in the sol- 

 vent. Above such a solution there will be a gas mixture of 

 the vapor of the solvent and of the several solutes. Inter- 

 change of particles will go on continually between the gas 

 solution above and the liquid solution below, but will not 

 be apparent for reasons similar to those expressed above for 

 liquid solutes. Also, if a solution containing a gas solute 

 be brought into contact with a mass of the pure solvent, dif- 

 fusion will take place of both solvent and solute, each devel- 

 oping its own diffusion tension in its own direction, just as 



