REVERSIBLE AND IRREVERSIBLE SYSTEMS UNDER INFLUENCE OF LIGHT. 369 
waiting with new solutions for a long time. I had therefore to choose the most 
suitable middle course. I waited only till the diminution of the E.M.F. in the dark 
became so small that it could but little affect the values of the deflections obtained. 
The deduction period of only one of the curves taken for every concentration was 
allowed to become complete, since all we required to know in these experiments was 
the maximum deflection only. The first deflection in each concentration is for 
obvious reasons the more reliable one. 
III. Plate WI4 of Jvhj 30, 31, 1903. Influence of Concentration, Table IV. 
In all the following experiments the distance of the acetylene from the quartz 
vessel was 116 centims., the intensity of the acetylene was 67 millims. (right and 
left), while the calibration of Nalder N2 was = 170 millims. right and left 
(ft) The system, used on July 29 and consisting of Ag-BrAg plates immersed into 
a decinormal NaBr solution, is again investigated. The E.M.F. in the dark = 1 '3 
centims. = 12*1x10 b volt, to the left. The resistance of the solution = 43'4 ohms. 
Nl gave 114 millims., N2 113 5 millims. deflection, average = 11375 millims. = 
120 x 10 ampere = 106x10 h volt. In Curve Nl the deduction period was photo¬ 
graphed to within 3 millims. from a-b. 
(b) A great part of the solution was removed and distilled water added. The 
resistance of the solution in the quartz vessel = 137 ohms. After an hour and an half 
the E.M.F. in the dark became = 6*0 centims. to the left, and was found almost 
constant during 15 minutes. N3 gave 114 millims., N4 116 millims. deflection 
= average 115 millims. = 123*3 x 10 -9 ampere = 118*5 x 10 -6 volt; the deduction 
period of N3 was photographed to within 6 millims. of its completion. 
(c) Removed all the solution, added distilled water, so that a very dilute solution 
was formed. The resistance was found to be 400 ohms. After about 15 minutes the 
E-M.F. in the dark was still 14 centims. to the right, but seemed almost constant 
during about 10 minutes. Curves N5 gave 80 millims. and N6 86 millims. deflection 
= average 83 millims. = 91*3 x 10~ 9 ampere = 108*8 x 10~ H volt. Since N6 was the 
last curve for the day I allowed its deduction period to become complete. We thus 
have :— 
cxw — (834*4+ 43*4) 114 = 100*1 x 10 3 = 106*3x 10“ 6 volt. 
= (834*4+ 43*4)113*5 = 99*63 x 10 3 = 105*8 x 10“ 6 volt. 
= (8 3 4*4 + 137) 114 = 110*7 x 10 3 = 117*5 x I 0 -6 volt. 
= (834*4 + 137) 116 = 112*7 x I 0 3 = 119*7 x 10 -6 volt. 
= (8 3 4*4 + 4 0 0 ) 80 = 98*75 x 10 3 = 104*9 x 1 0~ 6 volt. 
= (8 3 4*4 + 4 00 ) 86 = 106*2 x 10 3 = 112*8 x 10~ 6 volt. 
Average of Nl, 2, 3, 4, 5, 6 = 111-3 x 10~ 6 volt. 
Average of the more reliable obser. Nl, 3, 5 : 109*7 x 10~ 6 volt, 
3 B 
xu pi; m in i 
in N2 
In (b) in N3 
in N4 
In (c) in N5 
in N6 
r. = 
VOL. CCVI.-A. 
