Energy per unit length of dislocation is Gb2/2. Dislocations dilates a closed packed crystal structure veryslightly, since at their cores the atoms are not close packed:dilation is b2/4 per unit length of dislocation. It is found that the density of a bar of copper changes from 8.9323Mg m-3 to 8.9321 Mg m-3. when it isvery heavily deformed. Calc (a) dislocation densityintroduced into the copper by the deformation and (b) the energyassociated with the density. Compare the results with the latentheat of melting of copper (1833MJ m-3) (b for copper is 0.256nm, Gis 3/8 E).