11 glass melting furnaces and individual parts thereof, namely, melting ends, refiners, forehearths, feeders, furnace superstructures; preheaters for combustion air, oxygen and charging stock; inserters and feeders for charging stock; heaters and coolers for glass melting furnaces; individual parts for glass furnaces, namely, mechanical agitators and dispensers for glass melt; oil and gas burners, including those for oxygen operation