I recently found an interesting reference in Israel Hibner's Mysterium Sigillorum of 1651.
Under a section on purifying lead, he states,
Aliud ex Theophrasto:
Melt Lead in an Iron ladle, fling into it a piece of Wax as big as a Bean, let it burn away, then cast it into cold water.
It seemed to me rather reminiscent of the classical projection of the waxy Philosophers' Stone onto molten lead. I had a quick look on the Internet for information about purifying lead with wax and found a number of sources, particularly one regarding the preparation of pistol balls from molten lead where one uses wax as a flux to remove impurities immediately before pouring into the mould. This was thus being used during the period of the popular accounts of transmutation. I wonder if the accounts of transmutation could initially have arisen from a misunderstanding of the use of wax flux by craftsmen, and later being elaborated and allegorised.
Does anyone know of any other accounts, say from the late 15th through to the late 17th century, of the use of wax in this way for purifying lead?
Last edited on Wed Oct 15th, 2008 12:55 pm by adammclean
THeophilus (12th century) uses tallow as a flux for tin when trying to coat iron objects in tin. The idea thus goes back a long way.
Biringuccio, writing in the 1530's says several things about fluxes, for example:
"First is the method of softening gold when it does nto sustain the bloes of the hammer because of some trace of lead or of something else it has picked up. This is melted in a cruicible and crushed glass is thrown in, or a little Sal Alkali with wax, or three or four pinches of powdered sublimate, after which it is heated well."
He also mentions the use of borax, saltpetre, tartar, sal ammoniac, prepared common salt, sal alkali or crushed glass for purifying metals before casting.
So yes, the process has been around long enough and widely enough that many people would have seen it, and no doubt it gave a few people ideas. Certainly when I have put flux into tin and lead free pewter (tin with antimony) because the surface is clouded with oxides and impurities, there has been an almost miraculous clearance of the muck, leaving a nice mirror clear surface.
Also in terms of melting points, it goes tin, lead, silver, gold, copper, Iron. In reality similar fluxes will probably work well for tin and lead, and difference but similar ones for silver, copper and iron. I suspect there will be a reason for his giving each metal its own flux.