994 
accurately gauged from a determination of the temperature coefficient 
of its resistances at hydrogen temperatures. 
Figs. 2 and 3 show the Harrcoefficient Ay at temperatures of 
290° K., 90° K. and 20°.5 K. as a function of the atomic percentage 
of Ag. The curves resemble those which give the electrical con- 
ductivity and the temperature quotient of the resistance as functions 
of the atomic percentage. (Cf. KaAMERLINGH ONNEs and Benet BECKMAN, 
Comm. N°. (30c). When silver is gradually added to pure gold, the 
Harreoeffieient at low temperatures diminishes, at first rapidly, and 
then more slowly, until, with a mixture of about equal quantities 
of Aw and Ag, a large change in the composition occasions only a 
very small change in the Harreffect. The lower the temperature 
the steeper is the descent of the curve. For instance, when a 
2°/, admixture of silver is added to pure gold the Harreoefficient 
diminishes 
at, f= 20°36 KE fram IS ELO EIO TLD ae 
ak. Wt 908K arom B Oe 6:6 tae 
at f=, 290° KK from 720 tor6is* x 10-5 
Hence a small Ag impurity in gold occasions only a small varia- 
tion of the Harreffect at 7 = 290’? K. which, however, becomes 
more appreciable at lower temperatures. On the other hand, as is 
evident from the measurements of A. von ErriNGsHauseN and W. 
Nernst'), E. van AvupeL’?) and A. W. Surrn ®, the addition of a 
small quantity of Sn or Sb to Bi, which exhibits an unusually large 
Harr-effect, occasions even at ordinary room temperature a great 
change in the Harr-effect. 
Ar In Fig. 4 are shown the curves 
An . e Rgoo 
ER ij |. Of the temperature quotients: en 
2900 
Benard 
om and ——— as functions of the atomic 
2000 
percentage of Ag. These curves: 
as =205H) | have the same general features as 
0 10 20 30.40 S0- 60 70 80 Jo 100 
— (lom 2 lg 
Fig. 4. In Fig 5 is shown the relation 
between R and 7 for some Au-Ay alloys. The course of the curves 
between 20°K. and 90°K. is not quite certain, as no observations could 
those of Figs. 1, 2, and 3. ° 
Dn A. v. ErriNGsHAUsEN und W. Nernst: Wied. Ann. 33, p. 474, 1888. 
2) E. van ‘AuBEL: C. R. 185, p. 786, 1902. 
3) A. W. SmitH: Phys. Rev. 32, p. 178, 1911. 
