application_number US 31091606 A description fig1 shows a rotor 1 which is rotatable around an axis a the rotor 1 comprises two hollow tube like arms 2 at the outer end of each arm 2 there is realeasably mounted preferably in a gas tight manner a piston 3 in the piston 3 there is accommodated a mold 4 having a funnel like inlet opening 5 which is directed to the axis a nearby the outer end of each arm 2 there is provided a first crucible 6 made of a heat resistant material e g silica glass or the like the first crucible 6 is mounted at a bottom of the arm 2 preferably in a gas tight manner the first crucible 6 is surrounded by an induction coil 7 which can be moved in an essentially vertical direction in an lower position not shown here of the induction coil 7 it does not surround the first crucible 6 so that the first crucible 6 can be rotated with the rotor 1 around the axis a within the first crucible 6 there is accommodated a second crucible 8 having a outlet opening 9 which is placed opposite to the inlet opening 5 of the mold 4 the second crucible 8 is made of a heat resistant material e g alumina y 2 o 3 graphite or the like according to a preferred embodiment of the invention the second crucible 8 is made of alumina magnesia.