199.    BENTON, A. F., AND WHITE, T. A.  Adsorption of Hydrogen by Nickel at Low Temperatures.  Jour. Am. Chem. Soc., vol. 52, 1930, pp. 2325-2336; Chem. Abs., vol. 24, 1930, p. 3937.

                  Adsorption of H₂ on Ni was studied at pressures 0-1 atm. and at 11 temperatures between –210° and 110°.  At a given pressure the adsorption is relatively large at the lowest temperature, decreasing to a minimum at between –200° and –175°, then rising to a maximum in the neighborhood of –100°, and finally decreasing again at higher temperatures.  At 600 mm. the adsorption is constant between –100° and 0°, presumably indicating the formation of a monomolecular layer of adsorbed gas in this region.  All adsorption values are easily reversible with respect to pressure.  However, on cooling to about –190° a sample previously brought to equilibrium at 0°, the adsorption does not decrease to the value obtained isothermally at –190° but reaches a new reversible equilibrium at which larger quantities of gas are adsorbed than at 0°.  For some unexplained reason, at –191° and –183° the adsorption increases in a discontinuous manner with increase of pressure.