AN article by A. J. Warner (Elec. Comm., 22, No. 1; 1944), in reviewing the physical and electrical properties of plastics, discusses the various types of plastic materials available, paying particular attention to their electrical properties, and also examines their physical limitations, since there is no 'all-purpose' plastic available for the variety of conditions encountered. In all cases, a compromise must be made between the electrical properties and the mechanical limitations inherent in the material. In the summary which is provided, which of necessity is incomplete and rather fragmentary, such data are collected and collated as will facilitate an intelligent selection of materials. It cannot be too strongly emphasized, however, that, in the present state of the plastic art, a mere tabulation of physical and electrical properties will not necessarily enable one to choose the right material for any particular application. There still exists and will always exist the need for the exercise of judgment and the use of the accumulated knowledge of the particular engineer having the problem under consideration.