as explained in detail below , the present invention is directed to an apparatus for feeding molten metal at a substantially constant low feed rate . as used herein &# 34 ; low feed rates &# 34 ; are those which do exceed 3 pounds per minute . low feed rated of the present invention may be as high as approximately 250 pounds per minute , however , in a preferred embodiment the feed rates of the present invention are within the range of from about 3 to 50 pounds per minute . the apparatus of the invention includes a receptical 10 for holding a maximum volume of molten metal 12 therein . as shown in the drawing the receptical 10 which is preferably of cylindrical configuration may include a refractory crucible 14 , or receptical , for containing the molten metal 12 therein . the crucible 14 may be constructed of aluminum oxide , or similar material which is capable or retaining without contaminating the molten metal 12 therein . a heater 16 should be provided around the refractory crucible 14 . preferably , an induction coil 16 is provided around the outer periphery of the crucible . by controlling the power supplied to such an induction coil 16 the temperature of the molten metal 12 in the crucible 14 can be controlled to within tight tolerances independent of the melting and feeding rates as discussed in more detail below . the induction coil 16 is supported in its position about the crucible 14 preferably through the use of a rammed refractory 18 . to protect the crucible 14 and the induction coil 16 and to provide a structural support for this assembly , a frame 20 preferably of metallic construction may be provided around the induction coil 16 . it will be understood by those skilled in the art that such frame may also act to support the rammed refractory 18 which holds the induction coil 16 in place . extending outwardly of the crucible 14 at a location at or near an upper portion of the crucible 14 is an overflow runner 22 . the runner 22 may also be constructed of a refractory material , such as aluminum oxide , which resists metal attack and does not contaminate the metal passing therethrough . it will be understood that the location of the overflow runner 22 as it intersects the crucible 14 wall determines the maximum volume of molten metal 12 that is retained within the crucible 14 . logically , if the amount of molten metal 12 exceeds such maximum volume the molten metal 12 flows from the crucible 14 through the runner 22 . to assist the flow of metal from the crucible 14 to the runner 22 is preferably provided with a slight downward taper as it extends outwardly of the crucible 14 as illustrated in the drawing . in a preferred embodiment the crucible 14 is provided with a baffle 24 which provides a barrier at the upper surface 26 of the molten metal 12 in the crucible 14 at a location near the runner 22 . such baffle 24 prevents slag , skim or other impurities which accumulate at or near the molten metal surface 26 from flowing through the runner 22 . a bottom portion 28 of the baffle 24 should be spaced from the bottom 30 of the crucible 14 to permit the flow of molten metal through such space . it will be understood that a series of baffles ( not shown ) may be provided to create desirable flow patterns or to entrap additional slag or other impurities prior to discharge of the molten metal 12 through the runner 22 as may be desired in certain instances . in the operation of the apparatus of the present invention a solid charge 32 of metal is advanced towards the molten metal 12 in the crucible 14 . as shown in the drawing , the solid charge 32 may be cylindrical , although practically any type of solid charge which can be advanced into the crucible 14 may be employed . preferably , the cross sectional dimensions of this solid charge 14 should be uniform throughout the length of the charge in order to insure that the solid charge 32 is melted at a substantially constant rate . the preferred arrangement for the apparatus of the present invention is illustrated in the drawing . as shown , the cylindrical solid charge 32 is supported from a butt 34 located at a remote end 36 of the solid charge . the solid charge 32 may be advanced through a preheating device , such as the second induction coil 38 , located immediately above the crucible 14 . such a preheating device 38 may be desirable to initiate and accelerate the heating of the solid charge 32 toward its melting point . a guiding device 40 which also serves as a coil protector may be located inwardly of the second induction coil 38 with respect to the solid charge 32 . this device 40 should have a cross sectional configuration matching , but slightly greater than , the cross sectional configuration of the solid charge 32 . the device 40 may be constructed of a refractory material such as aluminum oxide . also , a substantially air - tight seal should be maintained to close a gap 42 between the upper end of the guiding device 44 and the outside wall of the solid charge 46 . likewise , a seal 48 should be provided between the bottom portion 50 of the guiding device 40 and an upper portion of the crucible 14 . such seals should extend around the periphery of the apparatus , and substantially prevent air or other ambient atmosphere from entering into and adversely affecting the operation after heating of the solid charge 32 has been initiated . the rate of advance of the solid charge 32 toward the molten metal 12 in the crucible 14 should be controllable to within tight tolerances . in a preferred embodiment , the butt 34 at the remote end 36 of the solid charge 32 may be attached by an appropriate coupling device 50 to a motor driven chain 52 . it should be understood by those skilled in the art that a cable , rod , belt or the like may be employed in place of the chain 52 . the chain 52 should be accurately responsive to incremental movements of a motorized drive system 54 . such drive system may be electrically operated , pneumatically driven , or driven by a rack and pinion or ratchet type device as may be desired . if necessary , the chain 52 may be threaded through gears , drives , or sprockets to effect speed reductions which may be necessary in the operation of the apparatus of the present invention . regardless of the advancing system employed , such system must be responsive to signals or commands indicative of the melting rates and , therefore , must be able to be controlled in relationship to the melting rate during the operation of the apparatus . it will be understood that the amount of metal 12 discharged from the overflow runner 22 is indicative of the melting rate . in the operation of the apparatus of the present invention the crucible 14 is provided with molten metal 12 . either molten metal 12 may be poured directly into the crucible 14 or a solid charge may be melted therein by the heat of the first induction coil 16 . the molten metal 12 in the crucible 14 is preferably superheated to a predetermined temperature . such superheated temperature should be chosen with consideration of the temperature loss that will typically occur in the system , particularly the temperature loss experienced by the discharged metal from the point of discharge to the point of entry into the system being fed , whatever and wherever such system may be . such superheat temperature should also be chosen with consideration of the melting rate of the solid charge 32 and the dissolution effect that the colder melted charge may have on the balance of the molten metal 12 in the crucible 14 . with the molten metal 12 maintained at a substantially constant superheated temperature , a solid charge 32 , preferably a cylindrical billet , is lowered through a preheating device 38 toward the upper surface 26 of the molten metal 12 in the crucible 14 . the preheater 38 preferably raises the temperature of the solid charge 32 from ambient or room temperature at the entry end of the preheater to within about 75 %, or higher , of the melting temperature at the exit end of the preheater 38 . as the solid charge 32 is moved further toward the molten metal 12 in the crucible 14 , and the lower face 60 of the solid charge 32 approaches the upper surface 26 of the superheated molten metal 12 melting of the solid charge 32 commences . it will be understood by those skilled in the art that , if any , molten metal 12 -- solid charge 32 contact may occur during melting . the preheating system 38 raises the temperature of the charge 32 to a point which facilitates melting as the charge is exposed to the ambient superheat temperature above the level 26 of the molten metal 12 in the crucible 14 . and , contact , even slight contact with the molten metal surface , facilitates smooth and effecient melting of the solid charge . as the solid charge 32 melts into the crucible 14 the amount of molten metal 12 in the crucible 14 exceeds the maximum volume determined by the location of the overflow runner 22 . therefore , as the maximum volume is exceeded , molten metal 12 flows from the crucible 14 through the overflow runner 22 . by constantly controlling the melting rate , the feed rate through the overflow runner 22 may also be controlled . therefore , it is necessary to maintain all of the variables in the apparatus of the present invention as constant as possible in order to control the molten metal feeding at a substantially constant , low rate . for example , by maintaining the preheat induction coil 38 and the superheat induction coil 16 at a constant temperature , and lowering the solid charge 32 at a constant rate the molten metal feed rate will be held substantially constant . however , in order to accommodate certain fluctuations in the system and to provide for a very tight control of the feed rate a device for measuring the feed rate may also be provided . such device should generate a feed rate signal , and the advancing mechanism should be directly responsive to such feed rate signal . thus , if a low molten metal feed rate such as 7 pounds per minute is desired and the feed rate signal indicates an actual rate of 6 . 5 pounds per minute , the advancing mechanism would speed the rate of advance of the solid charge 32 , slightly , in order to compensate for the reduced feed rate and to bring the actual feed rate to the desired level . as mentioned above such low , constant heat rates may be used to feed a variety of metal production facilities . preferred systems which require low , constant feed rates include powder atomization systems , continuous casting systems and drip casting systems , and by the process of the present invention such systems may be operated in vacuum . what is believed to be the best mode of this invention has been described above . it will be apparent to those skilled in the art that numerous variations of the illustrated details may be made without departing from this invention . for example , a plurality of solid charges may be simultaneously or successively advanced toward a crucible . such a multiple solid charge system may be employed to insure the maintenance of a continuous system which permits melting and feeding to be maintained while one of the nearly melted solid charges is being replaced with a new charge . also , a plurality of overflow runners may be employed in the apparatus of the present invention in order to feed a plurality of metal producing systems .