318 
PostTscRIPT. 
[V. Bismuth crystals. 
§ 18. Hatr-effect in bismuth crystals. We were not very successful 
with some of our measurements upon the rods cut in various direc- 
tions from a erystal which had been formerly used by van EVERDINGEN 
in his researches, and we had therefore meant to postpone the com- 
munication of our results until we had obtained a complete series 
of determinations for various positions of the axis; just as we go to 
press, however, the important paper by J. BecqurrEL in the Comptes 
Rendus for 24th June 1912 reaches us, so that we now publish the 
result which we had already obtained for the case treated by Lownps; 
it is given in the following Table. 
TABLE XIII. 
Harr-effect in a Bismuth crystal with the axis perpendicular to the field. 
T = 290° | T = 20°3 
| 
| ip SA REE Ee | 8 En a | 
| | | 
H | RH | R | H RH | 
| 
pee joe ae ere 4 — | 
2010 | 20.0103 —995 | 1850 | 180X10: | +9.72 
| 
3140 30.6 Bis | 3700 26.0 +7.03 | 
5810 38.6 —6.58 || 5800 | 33.6 +5.79 | 
| | 
8250 42.1 —5.11 || $700 | 43.7 + 5.02 
| 10270 | 443 —431 |: 11080 | 53.1 +479 | 
| | | 
At hydrogen temperatures / is positive and approximates to a 
constant value; at ordinary temperature it is RH corresponding to 
negative values of Zè which approaches a constant value. It is possible 
that small impurities exert considerable influence upon these changes, 
and it would therefore be risky to conclude from the fact that the 
value of R at hydrogen temperature which we have found is not 
greater than that found by Lownps for one direction in liquid air, that 
no change of any importance takes place between the latter tempe- 
rature and that of liquid hydrogen. (The resistance measurements 
show that Lownps’s bismuth plate was freer from impurity than ours). 
