CONDUCTIVITY OF MIXTURES OF ELECTROLYTES—McINTOSH. 121 
solutions containing sodium chloride and hydrochloric acid,— 
electrolytes whose ionic velocities differ from one another much 
more than those of sodium and potassium chlorides. 
The expression for the conductivity of a mixture of equal 
volumes of solutions of two electrolytes 1 and 2, which contain 
n, and n, gramme-equivalents per unit of volume respectively, 
the ionisation coefficients of which, in the mixture, are @, and a,, 
the molecular conductivities of which at infinite dilution are 
fio1 and o2, and which so change in volume on mixing that the 
ratio of the volume of the mixture to the sum of the volumes 
of the constituent solutions is p, 1s 
Gg = 5 (4 Ny Ho1 +42 No Pia): 
a 
In order to caleulate the conductivity of such a mixture 
therefore. the seven quantities in this expression must be known. 
The ionisation co-eflicients a, anda, are determined by the 
graphical process referred to above, from series of observations 
of the conductivities of simple solutions of the constituent 
electrolytes. The conductivities at infinite dilution are deter- 
mined by similar observations with very dilute solutions. The 
concentrations may be determined by analysis, and the quantity 
p by density measurements. 
I intended at the outset to determine all these quantities 
myself, in order that the data of calculation might apply to 
exactly the same electrolytes. But owing to the fact that the 
electrolytic cell, to be used in the determination of conductivities 
at infinite dilution, although ordered months ago, did not arrive 
in time, I am compelled to use Kohlrausch’s values of the con- 
ductivities at infinite dilution for the electrolytes examined. 
Determination of Conductivities. 
Kohlrausch’s well-known method with the telephone and 
alternating current was used. The apparatus was supplied by 
Queen & Co., of Philadelphia, and consisted of a German silver 
