^{page 160 note *} “An Experimental Analysis of the Losses by Evaporation of Liquid Air contained in Vacuum Flasks,” by Briggs, H., Proc. R.S.E., xli, p. 97.Google Scholar

^{page 160 note †} Ibid., pp. 98, 99.

^{page 160 note ‡} Ibid., p. 107.

^{page 161 note *} The manner of construction of the vessels, the selection of suitable metal and solder, the process of testing prior to evacuation, and the method of evacuation are dealt with in detail in the forthcoming Report of the Oxygen Research Committee.

^{page 167 note *} The pressure-reduction factor (i.e. the relation between the pressure in a given space before and after the charcoal is brought into action by being cooled to liquid-air temperature) is discussed in a paper (“Prehensility: a Factor of Gaseous Adsorption,” Proc., xlii, 1921–2, p. 26) which one of us read to the Society in 1921. The method of investigation, then pursued, depended on an experimental observation of Dewar, supported by the theoretical results of Williams, to the effect that the adsorption isotherm is virtually a straight line near the origin. Our own observations, set forth in that paper, bear out that view, but experiments now being conducted at Oxford on behalf of the Oxygen Research Committee point to the probability of a departure from the linear relationship in the isotherm at extremely low pressures. The matter receives attention in the forthcoming Report of that Committee. It therefore seems not unlikely that, with the order of pressure obtaining in Dewar flasks, the pressure-reduction factor will prove to be much greater than the one (namely, 1000) assumed in this argument. From the present point of view, the only effect of such a change would be to emphasise considerably our conclusions as to the relative importance of the radiation and conduction loss of these flasks and in regard to the needlessness of very fine evacuation by pumping. Evidence of a high pressure-reduction factor is provided by the results obtained with container No. 12.