134 
MESSRS. W. R. BOUSFIELD AND C. ELSPETH BOUSFIELD 
two errors. An approximate straight-line law was found to exist between h A s 
and x> As being the specific heat depression, i.e. , the difference between the specific 
heat of water and that of the solution, h As is proportional to the molecular specific 
heat depression. Though the relation turns out to be not strictly accurate, it enables 
closer final values to be obtained than by taking the mean values of two experiments 
in which the error might be in the same direction in both. The values of h As for 
all the solutions were plotted on the corresponding values of x, and the best straight 
line was drawn through all the points so plotted, the lines being expressible by 
h As - A + B x . 
For instance, in Table IX. are set out the experimental values for the specific heat 
of KC1 solutions at 7° C., together with the values of A s 7 calculated from the 
expression 
h As 7 = —92'14 + 2'4 X 7- 
The differences from the means of the experimental values are also set out. 
Table IX.—Specific Heats of KOI Solutions at 7° C. 
No. of solution. 
h. 
St, 
observed. 
Mean 
values. 
XT- 
A S? , 
calculated. 
calculated. 
Difference 
from mean 
value. 
I. 
16-362 
3-210 
3-206 
3-208 
45-12 
0-987 
3-206 
— 2 
II 
23-785 
3-429 
3 • 436 
3-433 
45-91 
0-758 
3 ■ 435 
+ 2 
III. 
35-296 
3-634 
3-627 
3 • 630 
46-71 
0-566 
3-627 
Q 
— o 
IV. 
53-743 
3-796 
3-792 
3-794 
47-37 
0-401 
3-792- 
_ 2 
Y. 
108-72 
3-981 
3-980 
3 • 980 
48-11 
0-214 
3-979 
-1 
VI. 
218-30 
4-087 
4-078 
4-076 
4-080 
48-53 
0-111 
4-082 
+ 2 
Furthermore in Table X. are set out similar figures for NaCl solutions at 20° C., 
which are of special importance, the relation in this case being 
h As 2i) = —69'30+2'074x20- 
Each of the six series of results was plotted in the same way and the resulting line 
used as a guide in fixing the final values of the specific heats. The values ol s 2 o—s 7 
and s 33 —s 2 o were also plotted upon P, and the curves so obtained were also used to 
detect abnormal values and to help in fixing the final values more accurately. In 
the case of the NaCl series at 7° C., the h As, x line broke up into two straight lines 
