Large bulk samples ( >150 g) of silver, silver-oxygen ( =0.12 wt.56), copper, copper-oxygen ( = O.O8 wt.%), gold, antimony and germanium have been undercooled approximately O.18 T where T is the melting point in degrees absolute. This large degree of undercooling has been achieved by melting in a slag of commercial soda-lime glass. The heterogeneous impurities which normally catalyse nucleation at small degrees of undercooling ( < 10 deg. C) are considered to have been removed by solution in the glass slag.
The grain structures of silver, silver-oxygen, copper and copper-oxygen alloys have been investigated and it is concluded that the change in grain size which occurs in silver and copper as a function of both undercooling and oxygen content results from recrystallisation.