218 Proceedings of the Royal Society of Edinburgh. [Sess. 
Hall Effect . — This was measured at temperatures of 15‘9° C. and 
101*5° C. 
Temperature of Plate = 1 5 9° C. 
Temperature of Plate = 101-5° C. 
Field. 
R x 10 7 . 
Field. 
Rx 10 7 . 
7,700 
+ 1-40 
7,800 
+ 0-95 
13,200 
+ 1-41 
13,770 
+ 0-98 
21,300 
+ 1-43 
21,300 
+ 0-99 
The coefficient R is positive, and increases slightly with increasing 
magnetic field, but decreases with increasing temperature. 
Temperature coefficient of R in field of 21,300 units = —0*0037. 
Aluminium. Thickness of plate = 0*25 mm. 
Thermomagnetic Effects . — These were measured at 40° C. 
Coefficient S in field of 22,700 units = — 6*3 x 10 ~ 8 . 
Q „ 22,700 „ 3-9xl0- 5 . 
Hall Effect . — This was measured at 14*5° C. 
Coefficient R in field of 21,600 units = — 1T5 X 10 " 7 . 
Discussion of Results. 
It will be seen from the following table that, although the Hall and 
thermomagnetic temperature effects vary both in magnitude and sign 
R 
from metal to metal, the ratio is for all the metals tested of the same 
k5 
positive sign, and does not vary greatly in magnitude. The ratio is not 
greatly affected by change of temperature, except in the case of nickel. 
Metal. 
Nickel 
Iron . 
Copper 
Zinc . 
Aluminium 
Field. 
Value of Ratio -5 . 
O 
Temperature 
44° C. 
Temperature 
100° C. 
8,500 
1*32 
1-83 
23,000 
1-37 
1-90 
8,000 
1-34 
1-44 
22,000 
1-36 
1-49 
8,000 
1-18 
1-15 
21,000 
109 
1T8 
8,000 
1-19 
1-07 
21,000 
1-20 
1-09 
22,700 
1-83 
