66 THE DIFFUSION OF GASES THROUGH 



The rate of diffusion appears as 



?'o = 0.0185 c.c./'day or 10% = 0.90 



a value which again approaches the normal result in Chapter II, and affords 



strong credence that the much more troublesome double-tube apparatus is 



unnecessary in practice. 



It is interesting to compare figs. 19 c and 20, which, though obtained 



with totally different apparatus, show identical thermal discrepancies. 



The new results obtained 

 with apparatus A have already 

 been discussed. Table 21 

 is a brief summary of the 

 values for the diffusion of air 

 through water as obtained from 

 totally different apparatus and 

 charges.! The untrustworthy 

 results (vessel A) are omitted. 



42. Diffusion of Hydrogen 

 into Hydrogen Through 

 Water. — The apparatus 

 (double tube, fig. 16) and ar- 

 rangements of results in table 

 23 are the same as in the pre- 

 ceding case of air. In the 

 present instance, however, an 

 artificial atmosphere of hydro- 

 gen had to be supplied. This 

 was obtained from a large gas- 

 ometer, a slow current of gas from the same passing over the surface of 

 the liquid day and night. The gas as introduced into the diver through 

 the lateral tube in fig. 16 was necessarily taken from the same gasometer, 

 so that the gases within and without the diver might be initially identical. 

 The case of diffusion of hydrogen through water, in the double-tube 

 apparatus, presents at the outset the usual meandering irregularity, here 

 due to the fact that the measurements were at first made in a temporary 

 medium of air. It was supposed, in view of the brief time of exposure, 

 that no serious discrepancy would be introduced; but the reverse is the 

 case. Consequently, for the remainder of the work, beginning about 

 October i, the observations were made in the almost entire absence of air, 

 the artificial atmosphere of hydrogen being kept in place during and after 

 the partial exhaustion incident to measurement. The results are now regu- 

 lar, showing the inevitable variations of the temperature of the room which 

 from the low solubility of hydrogen are insignificant in comparison with air. 



Fig. 2 1 . — Chart showing loss of standard volumes 

 of gas in diver in lapse of days. Diffusion 

 of hydrogen through water. 



