191. Many years ago I was employed as melter in a bullion assaying establishment, and was often called on to refine gold, which was done by granulating and re-fusing with nitre and borax, in a sand pot. It often happened that the crucible broke in the furnace, causing a great deal of trouble.

Knowing that the pots were attacked not only by the metal oxides produced in the refining, but also by the potassa resulting from the decomposition of the nitre, it occurred to me to mix some clean quartz sand with the nitre, which answered so well that I never afterwards had a pot broken in the furnace.