12 



S. R. Williams 



these values in our equation N= 



m n 



338X 



326.7 

 374-7. 



48. 



:230c 5. 



374-7 



The order as found for the liquid is that of the D y line in photo- 

 graph No. 3. For the D x line in No. 4 we add 338 to 2300.5 == 

 2638.5. The ratio between these two orders, 



vVliquid 

 iVair 



2638 5 



= i-3336. 



I978-5 



For the D 1 line in No. 3, the order for air would be the order 

 for liquid at that point, divided by the index. 



2300.5 



=1725.0. 



1-3336 



From these two orders of air and liquid for the D x line, the 

 orders for all other points in the spectrum may be calculated and 

 counted from the photographs. 



In counting the bands, they were laid on a dividing engine 

 under a micrometer eye-piece, and as the photographs were 

 shifted under the cross wires, the bands were counted, the frac- 

 tional part of a band being estimated only to tenths. 



The results from all of the photographs shown were obtained 

 in the manner described above and are tabulated below. 



Plate I— Triple Distilled Water. 7;/ =338. Temp. 22°. 



140 



