132,266. Gaskill, J. A. Sept. 3, 1918, [Convention date]. Crucible furnaces. - Relates to a liquid or gaseous fuel furnace for melting steel &c., rereducing refractory ores, annealing or heat-treating metal articles, e.g. high-speed tools and dies, milling-cutters, &c., and heat-treating metals where complete exclusion of cold air is required, and consists of means for heating the air supply for combustion, a releasable support for the crucible, and a special shape of furnace chamber. The furnace chamber is surrounded by a hollow annular casing to the lower end of which air is admitted tangentially by a pipe P. The air, thus given a whirling motion round the hot furnace wall, is led from the top of the casing by pipes L to the burners N, which enter the furnace chamber tangentially but in an opposite sense to the pipe P. The refractory lining of the furnace chamber has a thickened intermediate part of which the lower shoulder S<2> deflects the flame &c. towards the crucible, while the upper shoulder S' gives rise to an expansion and retarding chamber for the flame and gases. The crucible support, formed with an opening E<1>, rests on doors C hinged at D and held in place by props G. The removable furnace cover has a central outlet T. As shown, the fuel gas or oil is introduced at the burners. According to the Specification as open to inspection under Sect. 91 (3) (a) the fuel may alternatively be supplied with the air to the heating- casing. This subject-matter does not appear in the Specification as accepted.