1893.] Waterhon.se — Electrical action of Light upon Silver. 27 



Solution of Potassium Carbonate. 



With a solution of one per cent, of anhydrous potassium carbonate, 

 the cell having been standing for about 14 or 15 hours, the cell-current 

 was very small, and the plate exposed to light, either daylight or sun- 

 shine, was found to be positive, the deflection in the former case being 

 + 22, and in the latter + 63'5, without the magnet. 



With tap water made alkaline with a few drops of ten per cent, 

 solution of the carbonate in about 60 c. c. of water, the exposed plates 

 were also positive and very sensitive on first exposure, but the current 

 decreased with further action of light, and in subsequent exposures 

 the plates were less sensitive to light. They also lost sensitiveness by 

 being kept in the cell. 



Solutions of Sodium Carbonate. 



With silver plates exposed shortly after immersion in 1 per cent, 

 solution of anhydrous sodium carbonate in distilled water, the plate 

 exposed to sunshine was positive, the deflection being about + 5 divisions 

 without the magnet. In subsequent exposures the plates were less 

 sensitive, but remained positive. 



With a stronger solution, at 5 per cent., the results were similar, but 

 the plates seemed somewhat more sensitive. 



Solution of Lithium Carbonate. 

 With plates exposed shortly after immersion in a I per cent, solution 

 of lithium carbonate in distilled water, the plate exposed to sunshine 

 was positive, the deflection being about + 6 divisions without the 

 magnet. The plates lost sensitiveness after the first exposure as well 

 as by keeping for 34 hours, but remained positive. 



Dilute Solution of Ammonia. 



With a solution of 4 c. c. of strong liquid ammonia in 100 c. c. dis- 

 tilled water, the cell having been left standing some 14 or 15 hours, 

 the plates were found to be exceedingly insensitive to light ; even with 

 the magnet the deflections in sunshine were only about 2 divisions, the 

 exposed plates being positive. 



Another pair of plates immersed in a freshly-mixed solution, 

 containing 2 c. c. of liquid ammonia in 100 c. c. of water, and exposed soon 

 after immersion, were also found insensitive, but not so much so as 

 the last ; the deflection on first exposure in sunshine being about 3 

 divisions, without the magnet. The current, however, decreased on 

 further exposure, and the same effect was observed in subsequent 

 exposures. After a short time no current was perceptible. 



The immersed parts of the plates showed no deposit. 



