Comment on ‘A physical interpretation of Cole–Cole equations and their ambiguous time constants for induced polarization models’ by James Macnae

SUMMARY Macnae recently presented a physical interpretation of the Cole Cole Complex Conductivity model in the case of porous materials with sulphides. According to his paper, the Cole Cole parameters determined from such model can be easily interpreted in terms of underlying physics. His model is partly based on the electrochemical polarization model of Wong to explain the relationship between the chargeability and the volumetric content of sulfide. None of the statements made by Macnae are however novel. That said, we agree with Macnae that the Cole Cole complex resistivity relaxation time, while broadly used by our colleagues, is quite useless in deciphering the underlying physics of the induced polarization problem.