Pans and pot are heated from separate fire-places.
In the former case, the first reaction is produced in castiron pans or " pots," very heavy castings of circular section, fired from below, either directly or by the waste heat from the mufflefurnace.
The flame issuing from the furnace by (o) is always further utilized for boiling down the liquors obtained in a later stage, either in a pan (p) fired from the top and supported on pillars (qq) as shown in the drawing, or in pans heated from below.
\\ the back end, first into a large dust-chamber (m), and then over or under boiling-down pans (p) .
As these do not come out sufficiently pure, they would not be marketable and therefore they are not allowed to be formed, but the liquid, while still hot, is either run into the boiling-down pans, or submitted to one of the purifying operations to be described below.