This effect was tested by constructing a copper hollow cathode lamp containing an elongated cathode. This cathode, which was machined from a block of copper without using lubricating fluid, had the same cross-sectional area as the circular hollow cathodes, but the height had been made five times greater than the width. Measurements of the absorption of copper atoms in a flame with the cathode oriented vertically or horizontally confirmed the above suggestions.
LITERATURE CITED(1) Alkemade, C. T. J., "Proceedings of Xth Colloquium Spectroscopicum Internationale," p. 143, Spartan Books, Washington, 1963.