48 
Copper . 
iron grate, to the bottom of which the air has free access 
through the bars : at the other end, opposite the fire place, 
is a high perpendicular chimney. The direction of the 
flame, when all the apertures in the sides of the furnace 
are closed up, is necessarily determined by the stream of 
air which enters at the grate and takes its course toward the 
chimney, whose opening commences about the level, of 
the melted matter, and is proportionate to the draught re- 
quired. In tending thither, it strikes upon the roof of the 
furnace, and being reverberated from thence upon the ore, 
soon melts it. 3 Watson* 274. 
Schlutter has given plates of the Cupola furnace : and 
in Rees’s Encyclopaedia, new edition, (chemistry plate 1) 
there is a section of a cupola furnace with the application 
of a double bellows, which I think unnecessary, though 
common abroad. The common lead furnace, which is 
also the copper furnace, is well described in that work, 
article “ Lead.” It is this : 
The reverberatory (cupola) furnace employed in smelt- 
ing lead, is made on the same plan with those used in 
puddling iron (Cort’s patent process.) differing however 
in size, and a few other particulars. The fire is made on 
one end, and the flame plays over the hearth, entering an 
oblique chimney at the other end, which terminates in a 
perpendicular one of considerable height. The length of 
the hearth from the place where the fire enters, to the 
chimney, is II feet. Two feet of this length next the 
fire, constitutes the throat of the furnace. The width of 
the same is four feet, and its depth about six inches. The 
length of the fire place is four ieet, equal to the width of 
the throat ; its width two feet, and depth three feet from 
the grate up to the throat of the furnace. The rest of the 
hearth is a concave surface, nine feet long, four and a half 
feet wide at the throat of the furnace, seven feet four inches 
wide at the distance of two feet from the hearth, seven 
