LIQUIDS AND AI^LIED EXPERIMENTS. 



69 



The diffusion of air through strong KCl shows at the outset a peculiarly 

 rapid march. This is probably due to the fact that, to remove air bubbles, 

 the water was placed under a relatively high partial vacuum. The rapid 

 diffusion observed is in correspondence with the restoration of a normal 

 amount of air to the water. Thereafter the march of results is fairly 

 regular, apart from the invariable temperature fluctuation. From a mean 

 line drawn through the observations, the coefficient of diffusion may be 

 found as follows : 



i'(, = 0.0072 c.c, day, or io^V' = 0.137 



These data are to be converted, as stated above, by deducting hir' jH of 

 their value where 11 = 65 and 7r=i.5, so that 8ir'/H = 0.044-/65 which is 

 not appreciable in its bearing on k. 



The coefffcient is thus smaller than the lowest result for air and water, 

 or quite small as compared with the normal datum for an air-and-water 

 system. It follows, therefore, that the intermolecular pores of water are 

 quite effectively stopped up by the presence of KCl molecules between 

 them. Diffusion proceeds much more slowly. 



It would be an interesting inquiry to find how different gases behave in 

 relation to this stoppage; but the work is not yet advanced enough to 

 warrant speculation on such questions. It is obvious, however, that from 

 extended series of results like the following, definite conclusions as to the 

 effect of density of solution and chemical constitution, etc., on the structure 

 of the molecular pores must eventually be reached. 



44. The Same, Continued. — The solution was now diluted with water 

 to about double the above volume, showing the density of p„= 1.063 at 23°. 

 This is equivalent to 9.9 grams of KCl in 100 grams of solution, or to i i.o 

 grams of salt in 100 grams of water. The vapor pressures are now larger, 

 tt' = 7r( I — 0.063) being the value inserted and holding as above stated for brine. 

 The reduction to KCl requires tt' = 7r(i —0.044), so that the correction 

 67r' = o.oi97r and in — {dvJdH)bTr' = — {vJH)bTr', the factor 57r7^ = 0.029/ 65 

 is too small to make its effect appreciable. In other respects the experi- 

 ments were made as above. Table 25 and fig. 23 show the results. 



Fig. 23. — Chart showing loss of 

 standard volumes of gas in diver 

 in lapse of days. Diffusion of 

 air through KCl solution. 



If a mean line is drawn through the data as a whole, the results are 



Vj)=o.oii5 c.c./day or io^*'k = o.209 



showing some increase of k as compared with the concentrated solution 



(io^°K = 0.137) ; but in relation to pure water by no means as large an incre- 



