1912-13.] Compressibilities of Solutions of Inorganic Salts. 289 
It will be seen that there is very fair agreement between /3 F and f3 c — 
in fact, that observed and calculated values agree within 2J-3 per cent. 
The four cases marked with a cross fall outside this limit. That two of 
these should occur in the case of the same solution, viz. KOH of con- 
centration 2 -94, seems to point to some undetected source of error in 
this case. The volumes are subject to an error of about '001 c.c., while 
the pressures are subject to an error of about '5 per cent. ; this corre- 
sponds to a possible error of about 3 per cent, in the compressibilities. 
We see then that, within the limits of error of observation, calculated 
and observed values agree ; in other words, it is possible, for all the 
solutions examined, to find a value of AK to satisfy the formula 
J_ A 
% d P~ v AK ’ B+ AK +i?‘ 
This value AK is a measure of the increase of internal pressure due to 
the added salt. It will be seen from the numbers in the last column of 
the table how AK varies with the concentration ; we see that in general 
increases with increasing dilution. For the sake of comparison, I 
quote in the following table some of Tammann’s values for calculated 
from the thermal expansion of the solutions, and my values obtained 
from observations on compressibility : — 
Na 0 COo 
NaOH 
KOH 
ZnS0 4 
Results from Expansibility. 
Results from 
Compressibility. 
c 
7'1 
3'59 
•910 
•371 
’186 
aK 
674 
380 
120 
80 
70 
aK 
c 
95 
106 
132 
215 
376 
c 
4'18 : 3'19 
1-59 
4-08 
2-08 
1-77 
1*42 
•71 
aK 
763 | 540 
286 
700 
360 
310 
250 
130 
aK 
c 
182 j 169 
180 
172 
173 
175 
176 
183 
c 
5-60 531 
2-66 
5*75 
2-94 
1-98 
1-20 
aK 
661 641 
340 
660 
340 
230 
160 
aK 
c 
118 121 
128 
115 
115 
116 
133 
c 
295 
1'88 
2-90 
1 47 
•99 
•59 
aK 
236 
146 
200 
110 
75 
45 
aK 
c 
80 
77 
68-9 
74-8 
76 
76 
c 
4-06 
1*62 
3-82 
1-95 
1-31 
•79 
aK 
251 
111 
260 
130 
90 
55 
aK 
c 
62 
68 
68-1 
66'6 
68-7 
70 
VOL. XXXIII. 
19 
