C C C C, [fig. 60.], is a horizontal section of the furnace over the grate, showing the width of the mouth-piece, or plate of wrought iron, which is 6 inches, and the opening which receives the muffle-plate.
[Fig. 61.] represents the muffle or pot, which is 12 inches long, 6 inches broad inside; in the clear 63⁄4: in height 41⁄2 inside measure, and nearly 51⁄2 in the clear.
[Fig. 62.], the muffle-plate, which is of the same size as the bottom of the muffle.