482 Proceedings of Royal Society of Edinburgh. [sess. 
The usual arrangement of the plate for measuring the transverse 
effect was used. The notation used agrees with that of former 
papers, only here the total, instead of the half -galvanometer read- 
ing of the transverse effect, was divided by the primary reading to 
obtain the effect per unit current : this multiplied by the thickness 
of the plate is the number given as transverse effect per unit 
current per unit thickness; this latter is proportional to the 
rotatory coefficient E. 
The galvanometer used was a d’Arsonval ; the uniform field was 
created by the ring-formed electromagnet previously used. 
The plates v/ere protected from air-currents, and, to avoid heating, 
a pause of several minutes was made between the different observa- 
tions. 
Alloys arranged in a thermoelectric series. 
Sign of effect 
Effect per unit current 
Wiedemann’s Lehre der Electricitdt, 
in component 
per unit thickness of plate 
Bd ii., s. 256-61 (Dritte Auflage). 
metals. 
for field, 5610 c.g.s. units. 
19 ‘5 Bismuth, 1 Antimony, . 
- + 
-1-17 
10 Bismuth, 1 Antimony, . 
- + 
- -5657 
4 Bismuth, 1 Antimony, 
- + 
- -5257 
Bismuth (pure). 
- 
- -2800 
2 Bismuth, 1 Antimony, 
- + 
- -1356 
19*5 Bismuth, 1 Lead, . 
-0 
- -0155 
9 ’8 Bismuth, 1 Lead, . 
-0 
0 
4*9 Bismuth, 1 Lead, . 
Antimony, .... 
-0 
-t -0137 
-1- 
4- -01752 
6 Antimony, 1 Zinc, . 
-t -1- 
-1- -01438 
806 Antimony, 406 Zinc, 121 Bis., 
+ -f - 
-h -1438 
806 Sb., 406 Zn., 
+ + 
-h -1056 
Sb., Zn., Cd., 
+ -f -t 
4- -3960 
806 Sb., 696 Cd., 150 Bis., . 
+ -t- - 
-h -2423 
1 Ah., 1 Cd., .... 
-1- -1- 
-t -1613 
806 Sb., 696 Cd., 
+ + 
4- -6065 
/with 2000 
Tellurium, 
o • « 1 J oiuus extra 
-t- z oi-< inserted in 
Vgalvanometer. 
If we compare columns (2) and (3), we see that neither the 
direction nor the magnitude of the transverse effect can he pre- 
dicted from a knowledge of its value in the metals separately : for 
example, a small quantity of antimony ( -i- ) added to bismuth ( - ) 
gives an alloy with an extremely large negative effect (see curve I., 
fig. 1, diagram I.). Again, an alloy of antimony ( + ), zinc ( + ), 
bismuth ( ~ ), has a positive transverse effect nearly ten times larger 
