I worked in a fire assay lab for 17 years where the term fulguration is sometimes heard. Fire assay is an ancient method for precious metals analysis. It’s a small scale refining procedure. In the metals assay community, the more common term for the phenomenon is blick. It describes the brief flash of light (latent heat of fusion) given off by the precious metal bead (the glob of metal that is the final product of fire assay) as the last bit of lead oxide and other flux constituents are oxidized and absorbed away from the bead. Sometimes I would peek into the furnace to view the blick which was often preceded by a vigorous and beautiful swirling of colors on the bead's surface. This was the very last thin layer of lead oxide. Perhaps norgatem has affected the efflux of lead from some hapless fire assayers’ cells. (Did I use that correctly?)