The process is carried out either in hand-wrought furnaces,or mechanical furnaces, both called " decomposing " or " salt-cake furnaces."
Since the work with ordinary hand-wrought salt-cake furnaces is disagreeable and costly, many attempts have been made to construct mechanical salt-cake furnaces.
The mixture is fed in continuously to the central pan (e), whence it overflows into the compartments (c'), (c 2), (c 3) successively until it reaches the circumference, where it is discharged continously by o and into the collecting-box (q), being now converted into salt-cake.
Although the consumption of salt-cake for the manufacture of alkali is now much less than formerly, since the Leblanc alkali process has been greatly restricted, yet it is largely made and will continue to be made for the use of glassmakers, who use it for the ordinary description of glass in the place of soda-ash.
Nor must it be overlooked that salt-cake must be made as long primary duty of preventing nuisance, but quite as much to showing manufacturers how to make the most of the acid formerly wasted in one shape or another.
