DILUTION OF CONCENTRATED SOLUTIONS. 



331 



6'66 molecules per 100 molecules, which is HC1 . 15H 2 0. For concentrations above 

 10 therefore when all concentrations are reduced in such a manner as to assume 

 HC1.15H 2 as the solvent a proportional relation is obtained between heat of 

 dilution and concentration. 



This may be best expressed by the equation 



= a 



c 



If c is expressed in gramme-molecules of solute per molecule of solvent, and a is the 

 tangent of the angle of slope of the portion referred to (4082), taking N as 1, 



= a(n-0'066G). 



If expressed in terms of dilution 



n = ^ and ^S = *f -0'0666a, 



N cN N 



and the total heat generated, when one molecule of solute combined with N\ molecules 

 of solvent is diluted till combined witli N 2 molecules, is expressed by 



N - 

 N, 



x, 



Giving Nj the value 2'6, which is about THOMSEN'S maximum concentration, and 

 N 2 the value 10, THOMSEN'S values give 3415 calories, while those obtained above give 

 3427 calories. For concentrations below 10 molecules of water the two curves nearly 

 coincide, so that the total heat obtained by diluting very largely would be nearly 

 the same. 



The following results (Table IV.) show the degree of accuracy with which the 

 equation 



^ = 4082 (-0-0666 , 



dN VN 



fits the results for concentrations above 10 molecules per 100 molecules. 



TABLE IV. 



