Explanatory notes
… waxed or impregnated), varnish, enamel, pitch, oil, etc. In certain cases the insulation is obtained by anodising or by … of a surface coating of metallic oxides or salts). (C) In certain cases a metal sheath (e.g., lead, brass, aluminium … of gas or oil, or as a supplementary conductor in certain co‑axial cables. (D) Sometimes a metal armouring …