The llou•e Experimental Regen erative Ga4-Fornace — Mr. llenry )1. Howe. in a paper read before the American Institute of Mining En gineers, February, 1910, describes a furnace used by him in experiments on the thermal properties of sla,gs. It was necessary to have command of a very high tem peratare, at least 1,400' 0. (2,552° F,). and to make such dispositions that the platii.um-ball used for a pyrometer, and the silicate or• silicates experimented on, should be at approxi mately the same tempera ture at the moment of withdrawing the former. The regenerative gas-fur nace shown in section in Fig. 11 is made with two regenerators, loosely filled with lumps of fire-brick. Through one of the regen erators at. a time part of the air used for combus tion is brought under pressure from a blower, the product a combus tion passing out through the other regenerator and to waste. 00111111On illu initiating gas is used for and is brought in alternately through pipes. With this gas is mixed a considerable quantity of air. brought alternately by the pipes H /F. It was found necessary to thns mix quite n large volmne of air with the gas before admitting it into the furnace, to prevent rapid deeompositiml of the gas with deposition of carbon, At intervals, usually of 5 min. each, the furnace was reversed by means of common three-way
gas-eoeks. Althongli only part of the air and none of I lie gas was pre-heated in this furnave, a temperature of 1,400° C. was reached in it ; the hearth of the furnace was made of a molded brick, with depressions for five platinum crucibles _V .1', and for the platinum-ball 31. Cru cible,: and bulk were introduced and removed through the doorway L, closed with a tightly fitting molded wedge-brick.
Refoiciory 1.1(118 for Gas- Foritores.—Clny fire-brick, of nearly pure silicate of aln mina fr(qe from iron, is usually employed in ordinary heating-furnaces. hut for the intense heat required in steel-melting furnaces a more durable material is needed. For the cools of snob furnaces silica hriek, composed of nearly pure quartz. with from l to '3 per cent of other materials. ehielly lime and alumina to give Minding quality. used. For the basic open hearth filninee there is required IL material will not he acted upon by basic• slag, and it the saute time will withstand Itighe4 temperatures. SI1111 a material is magnesite brink, made from carbonate magnesia. when burned about 90 per cent of magnesia mad 10 per vent of silica and oxides of alumina and iron.