vo 
Physics. — “On tiv Marr effect, and on the change in electrical 
resistance in a inetynetic field at low temperatures. VIIL. The 
Harregjeet in Tellurium and Bismuth at low temperatures 
down to the melting point of hydrogen”. By H. KaAMERLINGH 
Onnes and Berner BECKMAN. Communication N°. 132d from 
the Physical Laboratory at Leiden. Communicated by Prof. 
H. KAMERLINGH ONNps. 
(Communicated in the meeting of December 28, 1912). 
§ 205). The Harrefject in Tellurium. The measurements were 
made with a short period Wi1rprMANN galvanometer. The primary 
current was /=0.2 amp. Two plates were investigated, both con- 
structed from the purest Merck tellurium. The first plate 7,7 was 
compressed in a steel mould, and the second plate 7,7; was cast 
in a steel mould. The first plate was very brittle. Both plates were 
circular with a diameter of 1 cm. The electrodes were platinum 
wires */, mm. in diameter, and were fused into the plates. To these 
platinum wires the leads were then soldered. The specific resistance 
and its temperature coefficient were different for the two plates; at 
T= 289°K. w‚, was twice as great for the first as for the second. 
The resistance temperature coefficient for 7e,; was always negative 
over the whole temperature region 289° > 7’ > 20°.3 K. Ter cn the 
other hand exhibited a minimum in the resistance below 7’= 70°K. 
The thickness of the piate 7e,; was 1.175 mm., its resistance 
Minti KK was 7 = 0:3 2 
20° 3 ia 
and again at dT 1 = d0 
at low temperatures therefore the resistance is considerably increased; 
cooling, moreover, caused an increase in the resistance at ordinary 
temperature, which is probably due to the production of small fissures. 
At 7 =290°- the specific resistance was 1.95 X 10° cg. s. We 
obtained the following results (2H and PR given in ce. g. s. units): 
(see table XXV p. 998). 
At 7'== 290° the specific resistance of 7¢,7; was 1.01 <10“ c.g. s. 
The plate was 1.88 mm. thick. The change in the resistance with 
temperature is shown in Table XXVI and in fig. 5%). 
Hence, as has already been mentioned, the resistance of the plate 
Tey attains a minimum at about 40° to 60° K. This behaviour is 
somewhat similar to that found by Dewar to be characteristie of 
1) The sections of this Communication are numbered as continuations of Comm. 
‘No. 1324. 
2) The diagrams are numbered as continuations of those in Comm. No. 1324. 
65 
Proceedings Royal Acad. Amsterdam. Vol. XV. 
