The Catalysis of the Ortho-Para Conversion in Liquid Hydrogen

Abstract

The catalysis of the ortho‐para conversion in liquid hydrogen is of importance for the quantity production of pure parahydrogen. Parahydrogen is of interest in itself: however, from a purely practical standpoint, if liquid hydrogen were to be kept for any considerable length of time, it would be much more economical to store liquid parahydrogen than normal (25 percent para) liquid hydrogen. Rough determinations of the conversion constant, both in the adsorbed layer of the catalyst and in the actual liquid, are given for activated charcoal and for silica gel onto which oxygen gas had been adsorbed. The heat of mixing of ortho‐ and parahydrogen was also measured, and found to be smaller than the accuracy of measurement.