316 
The change of the Hatt coefficient on cooling to the temperature 
Rrass : 
of liquid air _T=® has been found by SmitH') to be 
Rr =293 
1.03 for Au, 1.095 for Ag, and 1.205 for Cu. 
It seems to be of great importance that the change in the Harr 
coefficient for Ag and Aw takes place chiefly below —190° C. and 
becomes practically constant again in the region of liquid hydrogen 
temperatures. This is also seen to be the case for palladium on 
comparison of the results of experiments by Brner BECKMAN upon 
palladium at liquid air temperature, which are not in agreement 
with those given by Smirx, and which will be published in the forth- 
coming paper by Berner Beckman. In connection with the different 
behaviour for copper, for which BECKMAN has already found an 
increase in liquid air although smaller than that given by Ssrru, the 
question arises if this cannot be accounted for principally by the 
influence of impurity. Experiments which we have already under- 
taken upon alloys — in § 12 we give one set of results — will 
enable us to decide the point. 
§ 11. Change of resistance of Au,i, Pd,r, Cu,r, in a magnetic 
field. 
From the measurements with these plates only approximate results 
can be obtained for this change on account of the smallness of the 
change in the already very small resistance. In the following table 
results which were obtained in fields of from 10000 to 11000 gauss 
are reduced to a standard field of 10 kilogauss. 
TABLE XI 
Change of resistance in a magnetic field 
H WEE EAN Gan Sea 
| 
| 
10 Kilogauss ee 1017)” 1.14 2) 0015 
| 
| 
10 5 | 149.5 
| | | 
While at ordinary temperature the change caused in the resistance 
by the field is extremely small, at hydrogen temperatures it becomes 
quite appreciable. 
1) A. W. Smita, Phys. Review, 30, 1, 1910. 
