High-field galvanomagnetic measurements are carried out on $n$- and $p$-type silicon in the concentration range corresponding to the metal-nonmetal transition. Abnormally large positive magnetoresistance is accompanied by a corresponding increase in the Hall coefficient with magnetic field. Expressions for resistivity and Hall coefficient are derived, and the predicted value of $\frac{\left[\frac{\Delta \rho \mathrm{}\left(H\right)\mathrm{}}{\rho \mathrm{}\left(0\right)\mathrm{}}\right]}{\left[\frac{\Delta R\left(H\right)\mathrm{}}{R\left(0\right)\mathrm{}}\right]}$ is consistent with experimental results.

• Received 26 June 1968

DOI:https://doi.org/10.1103/PhysRevLett.21.752