THERMAL CONDUCTIVITY OF WATER. 
543 
The temperatures at which the experiments were made have varied from 12° C. to 
17° C. I have not yet made any attempt to trace difference in conductivity corre¬ 
sponding with different temperatures of the water. 
I have also commenced experimenting on the conductivity for heat of saline 
solutions, but I am not yet prepared to give numerical results that I should consider 
satisfactory. In order to make a comparison between the conductivity of water, and 
that of a liquid other than water, it is necessary to know the specific heat of the liquid, 
or, in the case of a saline solution, of the saline solution at the density which it has 
in the experiment on conductivity. Solution of sulphate of zinc has been experi¬ 
mented on in a preliminary way for conductivity, and its specific heat at various 
densities has been determined. I hope, however, with improved apparatus furnished 
by means of a grant from the Government Fund of £4,000, to be able soon to give 
much better results than I can offer at present. 
Table I.—Conduction of heat by water. Series of thermometer readings taken with 
arrangement of fig. 1, December 10, 1873. Time, 1.30 p.m., to 3.30 p.m. Thermo¬ 
meters A, B, I, C, as shown in fig. 1. 
Time. 
Thermometers. 
A. 
B. 
I. 
0 . 
1-30 
140-5 
113-05 
38-95 
61-7 
•35 
1431 
1138 
39-35 
•40 
145-0 
114-9 
40-15 
•45 
147-2 
115-75 
40-8 
•50 
148-45 
116-5 
41-05 
•55 
149-45 
116-5 
41-15 
2-0 
151-6 
117-15 
41-9 
•5 
152-95 
118-15 
42-3 
•10 
154-45 
118-85 
42-65 
•15 
157-95 
119-85 
43-05 
•20 
159-95 
120-5 
43-75 
•25 
161-95 
121-5 
44-05 
•30 
163-4 
122-0 
44-6 
61-75 
•35 
166-3 
122-6 
45-1 
•40 
168-0 
123-6 
45-9 
•45 
169-3 
124-3 
46-25 
•50 
170-0 
124-65 
46"6 
•55 
170-1 
124-85 
46-65 
3’0 
170-95 
125-45 
47-05 
•5 
174-0 
126-85 
47-95 
•10 
176-05 
128-0 
48-5 
•15 
178-2 
129-0 
49-15 
•20 
180-3 
129-65 
49-95 
•25 
181-5 
130-2 
50-05 
•30 
182-6 
130-85 
50-6 
62-05 
