There are other properties besides density and solubility that can be measured precisely and expressed in numbers. Such another property is the melting point, the temperature at which a solid substance melts to form a liquid. On the other hand, there are also interesting physical properties of a substance that are not so simple in nature. One such property is the malleability of a substance一the ease with which a substance can be hammered out into thin sheets. A related property is the ductility the ease with which the substance can be drawn into a wire. Hardness is a similar property: we say that one substance is less hard than the second substance when it is