The Hall Effect in a Bismuth Crystal

The Hall effect has been measured in plates cut in different directions from a single large crystal of bismuth. At room temperatures when the field H is perpendicular to the trigonal axis, a negative Hall coefficient R is obtained, decreasing from about 15 for H=1000 gauss to about 7 for H=8000. For H parallel to the trigonal axis a positive coefficient of about unity is obtained, increasing slightly with the field. At -186^ R is positive for all orientations of the axis and decreases as H increases. The maximum R observed at -186^ was + 15 at H=600. A plate made of compressed bismuth powder gave R=+7, approximately, at -186^. Beckman found large negative values of R for similar plates at this temperature. The Hall e. m. f. cannot be resolved into positive and negative components at -186^ in the way suggested by Becquerel.