348 
MU, W. C. D. WHBTHAM ON IONIC VELOCITIES. 
solving them in about 70 cub. centims. of water. An aqueous solution of ammonia 
was then added to the copper solution till the deep blue colour was formed. The 
same volume of ammonia was next run into the ammonium chloride solution, and 
both were made up to 100 cub. centims. This gave solutions whose strengths were 
0 1 monad grin, equivalent per litre. Their specific resistances were found by the 
method used by Kohlrausch and Fitzpatrick, and came out 157 X 10® (for the 
CuCl,) and 117 X 10® (for the NH^Cl) in C.G.S. units for the cubic centimetre. 
The solutions were carefully run into the velocity tubes, and the current sent 
through them and a low-resistance galvanometer in series. T'he galvanometer had 
jireviously been graduated by sending the current from a single freshly-prepared 
Daniell cell through it and through a known resistance, and noticing the deflections 
as the resistance was varied from 11,000 ohms to 150 ohms. 
Graduation of Galvanometer. Zero 1°'9. 
Oliuis. 
Deflection. 
Ohms. 
Deflection. 
11,UU0 
O 
= 5-8 
1,600 
= 3^5 
10,000 
6T 
1,400 
42'5 
9,000 
6-7 
1,200 
45-9 
8,000 
7'4 
1,000 
49-8 
7,000 
8-2 
900 
521 
6,000 
9-8 
800 
54-5 
5,000 
11-5 
1 700 
57‘0 
4,000 
15-4 
I 600 
69-9 
3,5()0 
18-7 
600 
63-2 
3,200 
21-0 
! 400 
67-1 
3,U00 
22-9 
350 
69-1 
2,700 
25-6 
300 
71-7 
2,.500 
2S-0 
250 
741 
2,200 
31-3 
200 
76-8 
2,000 
33-7 
150 
79'4 1 
1,800 
-36'6 
1 
The resistances were then again increased to 400 ohms = 67°'l, 1200 = 45°‘9, and 
3500 = 18°'7—numbers identical with those first obtained. 
Copper and Ammonium Chlorides. Velocities. Current upwards. 
Galvanometer. 
Time. 
Position. 
O 
74'7 
10.50 
32-4 1 
1 so n 
32-2 J 
>1’70 centims. per hour. 
4.0 
23-41 
V- 
23-5 J 
> 2o 0 J 
