564 Proceedings of the Royal Society of Edinburgh. [Sess. 
potassium, rubidium, and sodium, the degree of dissociation is equal to 
— ; and further, that this holds also for the solution of hydrochloric acid of 
the concentration having maximum conductivity. 
To judge by the ionic concentrations calculated in this way, we should 
expect that a solution slightly more concentrated than that having maximum 
conductivity would precipitate sodium chloride from its saturated solution, 
but we should not expect it to precipitate any of the other salts from their 
saturated solutions. 
If we take the hypothesis of a tendency towards maximum specific 
conductivity as a guide, we are led to expect that such a solution of hydro- 
chloric acid would precipitate all four salts from their saturated solutions. 
The first trials were made by simply mixing the respective solutions in 
test-tubes at room temperature. The final experimental tests were conducted 
as follows : — 
To ensure saturation, the salt solutions contained in glass-stoppered 
bottles were shaken for some hours along with a large excess of the solid 
salt. Some of the solution was then drawn out by a pipette through a plug 
of cotton-wool, and at once transferred to another stoppered vessel. The 
clear portion of saturated solution thus obtained was then mixed with from 
3 per cent, to 5 per cent, of its volume of the solution of hydrochloric acid 
to be tested. From first to last the temperature of the several solutions was 
kept at 18° C. to within one-hundredth of a degree. 
Table I. 
I. 
II. 
III. 
IV. 
V. 
VI. 
VII. 
VIII. 
Electrolyte. 
Concentration 
in mols./litre 
—c. 
Specific 
conductivity 
K 18 o. 
Molecular 
conductivity 
K 
h «. 
Degree of 
dissociation 
a~— • 
/lL 00 
CO* 
Ca t 
24)2 
NaCl . . 
5*44 
0'217 
399 
110-3 
0-36 
1-96 
0-96 
KC1 . . 
3-98 
0333 
83-7 
131-2 
0-64 
2 55 
1-26 
RbCl . . 
5*88 
0-442 
75-2 
133-5 
0-56 
3-29 
1-63 
NH 4 C1 . 
5-67 
0 420 
74-2 
130T 
0-57 
3-23 
1-60 
Max. HC1 
5*46 
0-765 
140-1 
384-0 
0-37 
2-02 
1-00 
* Ca = calculated ionic concentrations. 
= calculated ionic concentrations relatively to HC1 max. 
Many experiments were made with the saturated solutions of each of 
the four salts. The results arrived at may be summed up as follows : — 
