# The diffusion of gases through liquids and allied experiments . of glass. H is thebarometric height diminished by the head equal tothe vapor pressure of water vapor, r the absolutetemperature, and R the gas constant of hydrogen.The latter applies at the outset only. Since M =18.09 grams p„=i3.6 g = 98i i? = 4i.4Xio^ the constant A = Mgp^/R = 0.005823. The hydro-gen used was obtained electrolytically from water,enough being introduced into the swimmer to justprevent flotation. In the course of time the gases contained in thediver will change from the influx of diffused air andthe efflux of hydr

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The diffusion of gases through liquids and allied experiments . of glass. H is thebarometric height diminished by the head equal tothe vapor pressure of water vapor, r the absolutetemperature, and R the gas constant of hydrogen.The latter applies at the outset only. Since M =18.09 grams p„=i3.6 g = 98i i? = 4i.4Xio^ the constant A = Mgp^/R = 0.005823. The hydro-gen used was obtained electrolytically from water,enough being introduced into the swimmer to justprevent flotation. In the course of time the gases contained in thediver will change from the influx of diffused air andthe efflux of hydrogen. Hence the gas constant Rof the imprisoned gas is not fixed in value. Sup-posing, however, all observations to be made or alldiffusion to occur at a certain mean pressure B andtemperature t; since for all gases Rp = RqPq, thelatter referring to the initially pure gas at the giventemperature and pressure (supposed, as stated, tobe constant during flotation); and since, finally,m = vp = vp, during and before flotation, therefore RoPQ T ^Pm Pa^ ^Pw Po^ ^. Fig. 5.—Loss of massof gas in diver in lapseof days. Diffusion ofhydrogen into air. (1) so that the variations of volume v are referred to in taking the quantityA = Mgp^/R constant. To pass from v to the mass m it will be necessary tomultiply A by p/po where the density p of the imprisoned gas is not known.I shall suppose that the variation of temperature and pressure during a longperiod may be eliminated by the method of least squares. Hence only thecoefficients of diffusion by volume, called k below, are determinable. Thecoefficient of diffusion by mass, k, can not, apparently, be found at once,except for a system of but one gas. Table 2 contains the observations made preliminarily with hydrogen, inso far as they are trustworthy. These and others are reproduced in fig. 5, LIQUIDS AND ALUED EXPERIMENTS. 9 m being shown in the lapse of time. The curve is at first nearly linear in itsdescent and thereafter is sharply flex

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