"fulguration." Webster's Third New International Dictionary, Unabridged. Merriam-Webster, 2002. http://unabridged.merriam-webster.com
(27 Jun. 2007).
Main Entry: ful·gu·ra·tion
Inflected Form(s): -s
Etymology: Latin fulguration, fulguratio sheet lightning, from fulguratus + -ion-, -io -ion
2 : the sudden brightening of a fused globule of gold or silver when the last film of oxide of lead or copper leaves its surface in assayinghttp://website.lineone.net/~petehutch/cupella...
When the film of oxide becomes so thin that the bright silver beneath can reflect the light through it, a decomposition of the light into its constituent colours takes place, and the most brilliant rainbow tints are seen upon the metal, their beauty being enhanced by the rapid rotation of the film. As soon as this film of oxide has been absorbed by the cupel, the splendid surface of the melted silver shines out (fulguration, coruscation, or brightening).http://www.onelook.com/?w=fulguration&ls=a
Quick definitions (fulguration)
(n.) The sudden brightening of a fused globule of gold or silver, when the last film of the oxide of lead or copper leaves its surface; -- also called blick.
(This definition is from the 1913 Webster's Dictionary and may be outdated.)http://preview.tinyurl.com/2458k3
Fulguration, s. (Met.) das Blicken, der Silberblick.