Single crystals of theγ-phase of the system Ag-Hg have been grown from a globule of mercury immersed in a suitable solution of silver nitrate. The effect of heat on these crystals has been studied by taking X-ray diffraction patterns. It is found that on heating the crystals, the single crystal rotation pattern develops diffuse rings of a powder pattern. On further heating, these rings develop into a sharp complete powder pattern while the rotation pattern disappears. Results are explained as due to the faulting “domains” in the crystal growing bigger and bigger. On heating further, the domains grow into randomly orientated crystallites at the expense of the original lattice. It is likely that crystallites may develop into theβ-phase amalgam at temperatures beyond about 80° C. and retransform to theγ-phase on cooling.