Abstract: An attachment for a radial arm saw to enable biscuit slot cutting includes a separate housing on said radial arm, means for attaching a biscuit slot blade, means for transmitting power to said blade from said radial arm, and means for manipulating said housing with said biscuit slot blade independently of said radial arm.

Abstract: A recreational game device which may be used indoor or outdoor for use with playing several skill games. Targets are located on the game device and are used for playing various games.

Abstract: A multiple hearth furnace is constructed from a plurality of cylindrical heating chamber modules, connected in a vertical configuration. Each module contains a hollow hearth, which forms a floor in the chamber, the hearth having an open portion approximately centered in the chamber floor. A rotating central shaft is disposed vertically through open portions in the hearths and is provided with projections for distributing material to be heated across the hearths. Heating of the modules is accomplished by passing heated gases through the hollow hearths. Material to be heated is introduced into the uppermost module, is distributed across the hearth, and is discharged into successively lower modules, after which material exits the furnace. Gases which form during the heating can be removed separately from gases used to heat the furnace.

Abstract: Metal sulfide ores which contain organic matter are oxidized by roasting in a multiple hearth furnace, wherein at least a portion of gases formed during the oxidation is recycled from a higher-temperature, upper portion of the furnace to a lower-temperature, lower portion of the furnace. The control of air pollution from the furnace is facilitated by making some volatile organics, otherwise vented from the furnace, available for combustion, and by increasing the sulfur oxide concentration in the furnace gases.