Class II

is best illustrated by the reverberatory furnace, used in puddling iron and for roasting and melting ores and metals. The roof is arched over from the fire-place to the hearth, and the flame is thus reflected or reverberated downward on to the hearth. In a puddling furnace, when used for roasting ores, the bed is greatly extended, sometimes to 60 feet. The bed is IMG:content-0194.jpg:[blocks in formation] IMG:content-0195.png:[merged small][graphic][graphic] IMG:content-0196.jpg:[ocr errors] Rotary Calciner. sometimes replaced by a revolving cylinder, inclined toward the fire-place, through which the flame pa es while the material fed in at the upper end is automatically discharged. Such are called rotary roasters or calciners. In the German furnaces for cupelling silver the whole roof of the hearth is made removable to facilitate repairs.