UQUIDS AND AIvUED EXPURIMBNTS. 



67 



The difftision coefficients of hydrogen, computed from table 23, are 



i'o = 0.080 c.c./day or io'''k = 3.4 



They are again larger than foimd in Chapter II ; but the differences are such 

 as might be ascribed to differences of composition, seeing how extremely 

 sensitive the method is to slight impurities in the diffusing gas, which can 

 not be kept rigorously pure. There remains the inherent temperature 

 effect, the influence of \vhich on diffusion proper (apart from solution) has 

 yet to be investigated, both for hydrogen and for air. It is noteworthy, 

 however, that the k of the present observations, /. c, in a diffusion column 



Table 23. — Hydrogen-hydrogen through water. Vessel H (double tube). AI— 1 1.653 

 grams; p,i = 2.^66; (7=41.85; float, 2r = 3.05 cm.; tube, 2^ = 3.4 cm.; vessel, 

 2r=4.6 cm. 



nearly constant in diameter, comes out larger than it was found above for 

 a widening column. In any case the true diffusion coefficient for rigorously 

 pure hydrogen is yet to be found, inasmuch as the small admixtures in 

 question have so marked an effect. Thus the gas in the gasom.eter which 

 is used for the artificial atmosphere, even if generated quite pure, soon 

 becomes appreciably less so, since it must suffer contamination with the air 

 diffusing through the water of the gasometer over which the hydrogen is 

 stored. Since stich large quantities are needed, mercury storage is nearl}- 

 out of the question. Hence the work with hydrogen was abandoned tem- 

 porarily at this stage, the coefficient last found, 10^^ = 3.4 ^or the volume 

 diffusion at 0° C. and normal pressure, being preferable. 



43. Diffusion of Air into Air Through KCl Solution. — The solution of 

 KCl contained, after mixing, about 120 grams in 600 c.c. of soltition. Its 

 density was found to be 1.1133 at 24.5°. From this a table of densities 

 Pj^was computed between 16° and 25°, assuming the expansion to be the 



