426 Lord Blythswood and Dr. E. W. Marchant. 



It is clear therefore that if the logarithmic law holds, the numbers in 

 column 6 should be equal for any given plate. 



Nickel Chloride N/8 Solution. 



t in mm. 



log. 



Diff. 



K. 



Diff. 



Eatio. 



3-3 

 5-0 

 8-4 

 16-0 



0-519 

 0-699 



0- 924 



1- 204 



0-18 



0-225 



0-28 



2-9 

 2-4 

 1 -8 

 1-0 



5 

 0-6 

 0-8 



0-36 

 0-37 

 0-35 



The value of C therefore = 0'36. 



And since C = 1 - log (A^) log Xrfi = 0*64 



and since T = 20 mm. A x = 0'22 (for water). 



Potassium Bromide N/10 Solution. 



t in mm. 



log. 



Diff. 



K. 



Diff. 



Ratio. 



3-3 

 5-0 

 8-4 

 11 -o 



0-519 

 0-699 



0- 924 



1- 042 



0-18 



0*225 



0-128 



2-4 

 1-92 

 1-36 

 1-0 



0-48 

 0-56 

 0-36 



0-37 

 0-40 

 0-36 



The value of = 0-38. 



And since C - 1 - log (M) log (XA) = 0*62. 

 and since T = 20 mm. = 0*2 1. 



Sodium Thiosulphate, 2 XX. 



t in mm. 



3-3 

 5-0 

 6 7 



8-5 



log. 



Diff. 



K. 



Diff. 



Ratio. 



0-519 

 699 

 0-826 

 0-929 



0-18 



0-127 



0-103 



2-85 

 2-0 

 1-44 

 1-0 



0-85 

 0-56 

 0-44 



0-47 

 0-44 

 0-43 



The value of C = 0-45. 



And since as above C = l-log(X 1 ^ 1 ) log(A. 1 y = 0'55. 

 whence (as above) Xi = 0*18. 



It will be seen, therefore, that the value of A was not constant for 

 water, and hence not for solutions, if they obey the same laws. This is 

 confirmed by observations made on plates where the penetrative power 

 was not sufficiently great to give a dense photograph. The variation 



