322 



Dr. J. H. Long on the 



removed salt, this excess rapidly diminishes, until at the end 

 of about thirty hours the titrations show a constant quantity 

 of salt diffused per hour. The time required for this constant 

 rate to be reached is not always the same, varying between 

 twenty-four and forty-eight hours. Another experiment, made 

 under exactly the same conditions as the above, with a similar 

 tube, gave results as follows : — 





Cub. cent. 



Time. 



ro A ^°- 



9-10 required 



64-0 



10-11 „ 



17-0 



.1-12 „ 



9-6 



.2-1 „ 



7-6 



1-2 „ 



6-4 



2-3 „ 



6-0 



3-4 „ 



5-6 



4-9 A.M. „ 



3*4 per hour 



9-11 „ 



1-9 



1-4 



i.Q 



The constant rate was reached here in about twenty-four 

 hours. Many other experiments gave similar results ; but in 

 no case was the time required less than twenty-four hours. 



As was stated, the velocity of the flowing water in the above 

 experiments was 40 cubic centims. per hour. Thinking it 

 possible that this might have some influence on the rate of 

 diffusion, experiments were tried in which this velocity was 

 very variable. The beaker was first filled with normal BaCl 2 

 solution, and after the constant state had been reached the 

 velocity of the water was varied, as in the following Table. 



For convenience, the amounts of diffused salt will be given 

 here and in the following in cubic centims. AgN0 3 used per 

 hour in titration. 



H 2 O in cub. 

 per hour 



42 



cent. 



n 

 20 



Cub. cent. 

 AgN0 3 per hour. 



... 1-17 



45 







... 1-17 



47 







... 1-22 



53 







... 1*18 



60 







... 1-15 



88 







... 1-05 



The change of velocity seemed to have no disturbing influ- 

 ence in this case. To decide the matter fully, other solutions 

 were operated upon in a similar way ; and the results are given 



