TO THEIR STATE OF IONIZATION—-MACGREGOR. 239 
data were available, the absorption spectra were similarly 
affected by elevation of temperature and increase of concen- 
tration. 
THE OCCASIONAL CONSTANCY IN THE DIFFERENCE BETWEEN THE 
MOLECULAR VALUES OF PROPERTIES OF SOLUTIONS HAVING 
THE SAME MOLECULAR CONCENTRATION. 
The difference between the values per gramme-equivalent of 
any property for two simple solutions, 1 and 2, of different 
electrolytes but of the same concentration, will be 
(CL yd ee eee (11) 
Now a in all cases diminishes as 7 increases. Provided there- 
fore, the values of the (J—k)’s have the same sign, and the rates 
of change of the @’s with concentration are inversely propor- 
tional, or approximately so, to the (/—k)’s of their respective 
solutions, we shall have (P,—P,)/n exactly or approximately 
constant. If we regard (P,—P,)/n as approximately constant 
when its absolute value changes with 7 only to a small extent, 
then the more nearly the (J—k’s) and the @’s are inversely 
proportional to one another the more nearly constant will 
(P,—P,)/n be. If, however, we regard this quantity as con- 
stant when its values for different values of n differ from one 
another by only a small percentage, then the magnitude of the 
(l—k)’s becomes of importance, and we may have (P,—P,)/n 
approximately constant, even though the (/—k)’s may be far 
from being inversely proportional to the @’s. 
In the case of certain solutions of moderate strength, this 
approximate constancy of (P,—P,) /n has been observed by 
Valson and Bender* for the density and the refractive index, 
by Wagner + for viscosity constants, and by Jahnt for the 
electro-magnetic rotation of the plane of polarization; and a 
very close approximation to constancy in the case of the specific 
* Wied. Ann., xxxix, (1890), p. 89. 
+ Ztschr. f. phys. Chemie, v. (1890), p. 31. 
t Wied. Ann., xiii, (1891), p. 280. 
