Ninety small cores of synthetic metalliferous ore were constructed from solid glass spheres averaging 0.5 mm in diameter, lead spheres 1.0 mm in diameter, and refractory cement. The lead content of the cores varied from zero to 50 percent by frame volume. The effective porosity was controlled by the manufacturing pressure and ranged from 10 to 20 percent. The cores were saturated with NaCl solution. The apparent impedance of the cores was measured with a modified Wheatstone bridge as a function of frequency and current density. The low-frequency effects of induced polarization were separated from the over-all decrease of impedance with increase of frequency by taking advantage of the dependence of these effects upon current density. The over-all decrease of the impedance with frequency and the polarization effects were found dependent upon the effective porosity and the lead content. Both the polarization effects and the over-all decrease of the impedance with frequency increased with decreasing porosity. The induced polarization effects at 10 cps attained a maximum at approximately 15 percent lead content. The impedance of a synthetic ore with a small lead content was found to be larger than that of corresponding cores barren of lead.

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