(Lat. ductilis), in Physics, that property of certain solid bodies which consists in their yielding to percussion or pressure, or admitting of extension by drawing, without an actual fraction or separation of the parts of their mass. Some bodies are ductile both when they are hot and when they are cold; as metals. Others are ductile only when heated to a sufficient degree; as wax and glass. Other bodies, again, particularly some kinds of iron called by the workmen red short, brass, and some other metallic mixtures, are ductile only when cold, and brittle when hot. Certain bodies are made ductile by the absorption of a fluid; as clay. It is on the property of ductility in metals that wire-drawing depends. The following is nearly the order of ductility of the metals which possess this property in the highest degree—commencing with the most ductile:—gold, silver, platinum, iron, copper, zinc, tin, lead, nickel, palladium, cadmium. The malleability of gold (which, like that of other metals, depends on its ductility) is such, that five grains may be made to cover about 270 square inches—the thickness of the leaf not exceeding 1-200,000th part of an inch. Dr Wollaston succeeded in obtaining a platinum wire of which the diameter was only 1-30,000th of an inch.