Superconductivity in noble gases. The gradient of the positive column of a discharge in noble gases is caused by losses of energy at the walls, chiefly through recombination of positive ions. In order to eliminate the influence of the walls more completely, Güntherschulze and Keller used a very ingenious method. The discharge was produced in a round flask of capacity 33 l, with a piece of magnesium suspended at the center of the flask serving as the cathode, and the inner surface of the flask, coated with sputtered magnesium, as the anode. Under these conditions the measurements, made at pressures from several to several tens of millimeters of mercury, gave for the “normal” gradient (the gradient in the absence of walls, whose magnitude is proportional to the pressure), divided by the pressure, in the case of argon no more than

\[ 0.002\ \frac{\text{volt}}{\text{cm}\cdot\text{mm Hg}} . \]

For neon this gradient, because of its smallness, could not be determined; for helium values from 0.05 to 0.19, *

\(\dfrac{\text{volt}}{\text{cm}\cdot\text{mm Hg}}\) as a function of pressure. The presence of a gradient in this case, in the authors’ opinion, may have been caused by impurities in the helium. For hydrogen, a value of \(2.40\,\dfrac{\text{volt}}{\text{cm}\cdot\text{mm Hg}}\) was obtained.

The authors attribute the cause of “superconductivity” in the noble gases to the Ramsauer effect, i.e., to a very strong decrease in the effective diameter of the atoms of the noble gases for electrons of low velocities. (A. Güntherschulze and F. Keller, “Zs. f. Phys.”, vol. 77, p. 703.)

B. Klarfeld