Joint Discussion on Damping and Eddy Current Tests

E. M. BROHL. It seems as though the physicists in this crowd in the case of the cartridge cases have been a little in advance of the chemists in the crowd. What I am curious about here, and the way this appears to me, without too much study, is that in season cracking we get an atomic distortion so that both by sound means and by magnetic means we are finding a reluctance of the atomic planetary system to line up in accordance with the so-called good metal. The point that is brought up, or rather that has not been brought up-and I think perhaps we could think of that from the chemical point of view-is that this season cracking as I am used to the stress-corrosion cracking, appears to act much as though it were copper oxide. You remember when YOU take copper oxide films in which we again use this distortion of the atomic system to allow currents to pass selectively in one direction only, we get results almost identical with what we saw on the oscillograph report. In other words, on the one section of this season cracking we had a trace of one phase and if you notice on the sections three and four of the numbered oscillograph trace we had what appears 180 deg. out of phase.