4H EXPERIMENTAL INVESTIGATIONS. 



Dilute muriatic acid. 



o 



Deflection by polarisation . ... 4 



Sunlight . . . . . . .10 



Blue glass ....... 7 



Yellow glass ...... 6 



Red glass 5'5 



Exposed platinum negative. 



September 10. Dilute nitric acid. 



o 



Deflection by polarisation i 



Sunlight ....... 5 



Exposed platinum positive. 



Dilute muriatic acid. Polished platinum plates. 



o 



Deflection by polarisation . . i 



Sunlight ....... 2 



Exposed platinum negative. 



September 14. Two sets, one of polished, the other of 

 platinised platinum plates, in dilute sulphuric acid, without 

 porous diaphragm. 



The polished plates gave : 



o 



Deflection by polarisation ... 2 

 With sunlight 3 



Platinised plates gave : 



o 



By polarisation ..... 3 

 With sunlight 4 



The pair with black platinum was then tried with a porous 

 cell ; and as it was not set aside for more than a few minutes, 

 to allow the polarisation to subside, the 



O 



Deflection by polarisation was , . 15 

 Increased by sunlight to ... 20 



Exposed platinum positive. 



