782 
the values of k given in the third column of the table are those 
which we obtain when we make use of a slightly different value 
of 2 0 , namely 5,65.10 5 cm. 
X k 
assuming assuming 
:X 0 = 5,63 l 0 = 5,65 
5,22 1,27.10 14 sec- 1 1,82.10 14 sec” 1 
5,40 1,66 . 1,79 . 
5,81 2,93 .. 2,60 . 
5,89 2,22 ...... 2^04 . 
Even allowing for the imperfect nature of the data at our disposal 
we must still admit that the approach towards constancy is unsa¬ 
tisfactory. This being so, it seems all the more remarkable that 
the value of k found in § 11 A by an independent method, viz. 
2,84.10 14 sec“ 1 
is of the same order of magnitude and fits well indeed with the 
results just given. 
In the following sdme other values of k : calculated in a similar 
manner by equation (5) § 8, are given. 
B. Dextrogyric copper tartarate and caustic potash solution 
Cotton, page 400); X Q = 6,57. 
X \ip\ cp 
5,62 2° 29' 0° 51' 
5,815 2° 16' 10 26' 
5,89 2° 00' 1° 34' * 
* Read from the curve. 
C. Laevogyric copper tartarate and caustic potash solution (Cot¬ 
ton, page 400); X 0 = 6,57. 
X j cp k 
5,62 2° 25' 0° 55' 1,71.10 14 sec“ 1 
5,815 2° 16' 1° 24' 2,17 . 
On the whole, the evidence, in the case of the substances investi¬ 
gated by M. Cotton, is not in favour of the simplest form of 
Theory, of that which takes account of only one class of vibrating 
electrons; and to carry out the process of verification with strictness^ 
k 
1,54.10 14 sec" 1 
2,22 . 
2,44 . 
