346 ON THE SURFACE TENSION AND 
these in the proportions as to volume requisite to prevent 
change of ionization on mixing, and then to measure and eal- 
culate the specific gravity of the mixture. For the exact mode 
of determining the ionization coefiicients, concentrations and 
volumes of the four simple solutions to be mixed, I may refer to 
my paper cited above. All the data required for the calcula- 
tions are given in Table VI, together with the calculated and 
observed values. The concentrations of solutions and specific 
gravities are expressed in terms of the same units as in pre- 
vious tables. The column headed “volumes” contains the 
volumes in ¢. e. of the Potassium and Sodium Chloride solutions 
mixed with 25 ¢.¢. each of the sulphate solutions. 
TABLE VI. 
CONSTITUENT SOLUTIONS. SPECIFIC GRAVITY 18° 
18° 
Concentration. Volumes ! 
= in c.c. of | Goncen- Caleu- |Differ- 
eee tration |Observ'd.| jated- | ence. 
CC JaCl. |2K S04. #NagSO4| oo of ions. 
K Cl. | NaCl z Kg O4 3 N a) 4 Solutions. 
.0500 | 0512} .0607 | .0611 3053 | .0445 | 1.00325 , 1.00319 |-0.0,6 
.0527 | .0536 1 .0640 | .0644 30.57 .0467 | 1.00839 | 1.00334 | — 5 
.0648 | .0659 | .0791 | .0800 30.88 .0568 | 1.00403 | 1.00410) + 7 
.0787 | .0800 | .0969 | .0984 31.25 .0683 | 1.00492 | 1.00500 | + 8 
1032 | .1063| .1287 | .1419 34.37 .0887 | 1.00664 | 1.00668) + 4 
1219 | .1265| .1552 | .1700 34.85 103 | 1.00795 ; 1.00789 | — 6 
ASLO S49) 1674 | ASS 34.99 112 | 1.00849 | 1.00847 | — 2 
1675 | 1736 | .2201 | .2374 35.42 141 | 1.01084 | 1.01092 | + 8 
.2008 | .2083 | .2702 | .2902 36.14 167 | 1.01810) 1.01317) ee 
.2380 | .2500 | .3225 | .3478 36.56 196 | 1.01556 | 1.01568 |+0.031 
The above table shows that in all except the last solution 
examined the differences between the observed and calculated 
values are either within or but little beyond (in three cases 
within and in six a little beyond) what I consider my possible 
error of observation. They are also about equally divided as to 
sign. Considering the large number of sources of error involved 
