It is pointed out that, although dielectric losses in certain materials are frequently attributed to the presence of particles of conducting impurity, any discussion as to the type and magnitude of loss produced by a given quantity and disposition of impurity is often extremely vague or entirely lacking. A description is given of some experiments with a suspension of water droplets in wax, the results of which did not agree with the predictions of Wagner's theory except when the suspension was kept at a temperature near to the melting point of the wax. The behaviour of a model inhomogeneous material containing spheroidal particles is investigated analytically and it is concluded that a minute amount of conducting impurity in the form of fine needles could produce a serious loss at low frequencies, although the effect of the same quantity of impurity in spherical form would be negligible.