Thomson Effect in Zinc Crystals

The Thomson coefficient, σ, is directly determined for a group of zinc crystal rods with orientations distributed fairly uniformly over the entire possible range. At 49.5^∘{}C and at 125^∘{}C the values of σ seem to obey the Voigt-Thomson symmetry relation, although not as good a check is obtained at the higher temperature on account of increased experimental error. The principal values obtained are: ${At 49.5^∘{}C, {{σ}}_{{⊥}},=0.98×{}{10}^{{-}6}cal.{coul.}^{{-}1}{deg}^{{-}1}}{{{σ}}_{{∥}}=0.38×{}{10}^{{-}6}}{At 125^∘{}C, {{σ}}_{{⊥}},=2.09×{}{10}^{{-}6}}{{{σ}}_{{∥}}=1.08×{}{10}^{{-}6}}$The values at 49.5^∘{}C are found to compare favorably with values for polycrystalline zinc calculated from Sommerfeld's theory of conduction, (0.32×{}10^-6 cal. coul.^-1. deg.^-1), and found by Borelius experimentally, (0.88×{}10^-6 cal. coul.^-1. deg.^-1). The increase of σ with increased temperature is greater than has been previously reported for polycrystalline zinc but is in approximate agreement with some earlier determinations by the writer. In addition, specific resistivity and temperature coefficient of resistivity are determined.