319 
Physics. — “On the Har effect and the change in the resistance 
m a magnetic field at low temperatures. UW. The Harr-efject 
and the resistance increase for bismuth in a magnetic field at, 
and below, the boiling point of hydrogen”. By H. Kameren 
ONNes and Brener Beckman. Communication N°. 129¢ from the 
Physical Laboratory at Leiden. 
V. Linear variation in strong fields. 
: 14°), Linear variation of the HA e fect, for bismuth in strong fields. 
As was suggested by J. BECQUEREL *;, the fact that the Harr effect 
ie bismuth in strong fields can be represented by a linear function 
of the field strength may be regarded as resulting from the compo- 
sition of the effect from two separate components. One of these is 
proportional to the field, and was found by us (see Comm. N°. 129a 
§ 4) to be always negative for plates of compressed electrolytic 
bismuth. The second approaches a limiting value, and, with our 
plates, was found to be constant at hydrogen temperatures, in fields 
greater than 3 kilogauss. 
That is to say, the law of linear dependence upon the field 
rigidly obeyed by the first component of BrecQveren, within the limits 
of experimental error in fields greater than 8 kilogauss. As an 
example we give in Table XIV values calculated from 
REL tap Be ta as ae ANN 
in which == 54.5 and: 6! ==42.10? 
(with both af and 6’ in absolute units), and alongside these we put 
values for T= 20°.3 K. taken from Table III. 
The linear form is found to be just as rigidly obeyed in the 
experiments made by Berner Beckman upon the same experimental 
material at the temperature of liquid air; for an account of these 
experiments we may refer to $ 3 of the Communication N°. 130. 
It is noteworthy that, in the case of the second component, satura- 
tion is most easily aftained at low temperatures. In this respect this 
component is analogous to the magnetization of a ferromagnetic sub- 
stance. The linear dependence of the first component upon the field 
strength recalls the behaviour of diamagnetic polarisation. In the 
region of very low temperatures the very rapid variation of a’ with 
the temperature can be represented by a simple empirical formula 
which was obtained by compounding the data given by Beckman for 
liquid air temperature (see Communication N°. 130a). From this it 
was found that 
/ 
1) The sections of this paper are numbered in continuation of those of Comm. 
No. 129a. 
4) G. R. 154, 1795, -1912. 
