I got interested in silver mining and extraction (see "Beehive Kilns.....) which led to copper, tin, lead and other things. Smelting and refining being among them.
Okay, I understand the fundamental idea. A simple picture shows it pretty clearly:
I grabbed some stuff from wikipedia on reverberatory furnace's out of convenience as I am tired tonight:
"Chemistry determines the optimum relationship between the fuel and the material, among other variables."
"Contact with the products of combustion, which may add undesirable elements to the subject material, is used to advantage in some processes. Control of the fuel/air balance can alter the exhaust gas chemistry toward either an oxidizing or a reducing mixture, and thus alter the chemistry of the material being processed."
I don't think I took them out of context. These are things that interest me. I guess they are called metallurgical furnaces as well. Metalurgy and chemistry interest me, too. I usually like to exhaust my understanding and research of a subject before I start asking questions, so I probably shouldn't even have mentioned the subject earlier, but I was trying to illustrate why I was digging around finding old blacksmith art and posting it. I always welcome input, comments and ideas, as you know, but I wasn't trying to derail this thread.