But even when the old type of reverberatory is preferred, as at the Argo works, at Denver, where rich goldand silver-bearing copper matte is made, the growth of the furnace in size has been steady.
The low percentage of sulphur in the roasted ore is little more than enough to produce a matte of 40 to 45%, and therefore the escaping gases are better fitted than those of most copper cupola furnaces for burning in a stove.
As the matte contains on an average o.
The largest furnaces are those of the Boston & Montana Company at Great Falls, Montana, which have put through soo tons of charge daily, pouring their melted slag and matte into large wells of io ft.
A combined brickand water-cooled furnace has been adopted by the Iron Mountain Company at Keswick, Cal., for matte concentration.