Dr. Anderson's hypothesis was thoroughly refuted. Hot liquids, like molten copper, do not absorb gases from their surroundings. They actually release gases. Also, the technique required the consideration of an "environmental cap" which could be as deep or shallow as you need to make the results what you want them to be.

Journal of Forensic Sciences V 42 #4, 1997. The surface analysis of copper arc beads—a critical review Howitt, DG
Department of Chemical Engineering and Materials Science, University of California, Davis, CA.

Abstract
The chemical composition of arc beads has been purported to reflect the local atmospheric conditions at the precise moment when the arc occurs. It has further been claimed that Auger analyses, taken from beneath the surface contamination layers of an arc bead, can be used to distinguish whether the arcing was the cause of a fire. The hypothesis is that because atmospheric gases are trapped in the arc bead when it solidifies, the concentrations of gases inside the bead will reflect ambient conditions when the arc causes the fire, but rich concentrations of combustion gases when it does not. A review of the literature on the solubility of gases in liquid copper indicates that there is no scientific justification for this hypothesis.