ON THE SPECIFIC HEAT OF AQUEOUS SOLUTIONS. 
151 
Values of Constants. 
KC1. 
B = 0-001132 
w c = 0'98592 
Er 0 = 36-804 
L = 24*83 
Es s = 123-4 
s s = 1"655 
NaCl. 
0-000854 
0-97551 
25-053 
2573 
142-1 
2-433 
The molecular heat Es s of the liquid solute comes out curiously high in both cases. 
Expressed in calories the molecular heats given above are 
KC1. NaCl. 
29-5 34-0 
According to the law of Dulong and Petit as supplemented by Kopp the 
molecular heats for the solids are both about 13 cals. Thus the molecular heats for 
the liquefied solutes are more than double those of the solids. The same phenomenon 
is to be noted in the case of ice, the molecular heat of which is 8"6, whilst that of 
liquefied ice is 18, again more than double. In both cases there are no doubt changes 
of state with rise of temperature which account for the difference. The figures 
seem to point to the fact that the liquefied solutes have like water a complex 
molecular structure which is altered by rise of temperature. 
23. Analysis of the Specific Heat of the Solutions .—The relations at which we 
have arrived enable us to analyse in a simple manner the isothermal changes in 
specific heat which take place on dilution of a solution. 
If we put E grammes of solute into H grammes of water then in one gramme of 
the solution we have present 
E 
E + H 
grammes of solute and 
H 
E + H 
grammes of water. 
Since 
s (E + H) = s s E + s M i? 
we can write As in the form 
_E (s w s s ) H (s w —s M ) 
E+H E+H 
That is to say, the specific heat lowering by the introduction of E grammes of 
solute into H grammes of water may be regarded as the sum of two components. 
E 
(1) The specific heat lowering due to the mere substitution of ^ grammes of 
solute for the same weight of water; 
(2) The reduction of the mean specific heat of the water from s w to s M . 
The result developed in Section 19 gives for NaCl 
s w s M = 25 73 A Xo /H. 
VOL. CCXVIIl.—A. 
X 
