My faultless breast the furnace is, the fuel wounding thorns; Love is the fire, and sighs the smoke, the ashes shame and scorns; The fuel Justice layeth on, and Mercy blows the coals, The metal in this furnace wrought are men's defilèd souls, For which, as now on fire I am, to work them to their good, So will I melt into a bath to wash them in my blood.

Every condition of combustion is thus violated, and the intended furnace is a mere gas retort.

No furnace can supply the place of it; for, though the furnace is an indispensable auxiliary in severe cold, and though, well managed, it need not vitiate the air, yet, like all contrivances for supplying heated air instead of heat, it has the insurmountable defect of not warming the body directly, nor until all the surrounding air be warmed first, and thus stops the natural reaction and the brace and stimulus derived from it.

The subliming furnace, shown in Figs. 5 and 6, is a plain cylindrical chamber, A, about 4 ft. diameter inside and 4½ ft. high, lined with firebrick, in the center of which is fixed the upright cast-iron cylinder or retort, C, of 1 ft. diameter, closed at top and open at bottom.