376 DR. MEYER WILDERMAN ON THE CHEMICAL STATICS AND DYNAMICS OF 
February 7, 1905, Plate 18 :— 
O'l norm. LiBr sol. gave : in Nl, 92 millims. deflection ; 
0'1 norm. NHfBr sol. gave : in N2, 98 millims. ; in N3, 98 millims. deflection. 
Intensity of acetylene = 21‘5, Nalder N2 = 16'05 centims., Nalder Nl = 21*2 centims. 
As the distance of the light from the systems was 116 centims., the thermo E.M.F.’s 
under my conditions of experiment could be neglected. 
The results obtained with KBr, NaBr, LiBr, NH,Br, confirm the results previously 
found that the E.M.F. created by light is independent of the cation. - 
VII. The Effect of Covering the Ag Plates with Different Coatings of AgBr on the 
E.M.F. obtained. 
In the course of this research the same Ag plates had many times to be polished 
again, and covered afresh with AgBr. Surveying the E.M.F.’s obtained with freshly 
coated Ag-BrAg plates (when one of the two sides of each plate was covered with 
shellac and paraffin) in the same solutions at different times, there* can be no doubt 
that there is no such thing as getting the same BrAg surface again. However well 
polished the plate may be, the AgBr surface is a conglomerate of crystals, which, 
according to the conditions of preparation (such as concentration of Br 2 in BrNa, 
time of action, temperature, &c.), are of a greater or smaller size, i.e. , in the same 
surface of the Ag plate different surfaces of the AgBr are exposed to light. We 
may call it “ physical variation of sensitiveness ” of the plates, similar to the 
phenomena observed with BrAg emulsions in the process of ripening. 
VIII. Ag-IAg Plates in O'l normal KI Solution ( without solid IK on the Bottom 
of Quartz Vessel) ( Plate N20 of February 19, 1903), Table VIII. 
In Table VIII. the investigation of the above system is given carried out with the 
arc between the 11th and 23rd of February, 1904. The direction of the current in 
the solution is always from the plate in the dark to the plate in light. The IAg 
plates were prepared in the dark through immersion of Ag jdates (polished, as 
described before, and covered on one side with the shellac and paraffin) into a solution 
of iodine in potassium iodide. We find, as in case of Ag-BrAg plates, that the 
E.M.F. created by light of the same intensity first gradually increases (15th to 19th 
February), after previous illuminations it then reaches an apparent constant value, 
or even begins to decrease (18th to 23rd February). For the law of intensity we 
get (February 17, with the blue screni) less good results than with the weak 
acetylene light: 125 2 x 45 = 70'3 x 10 4 and 92 2 x 78 = 66 x 10 4 . The ratio of the 
deflections of the total light passing no screen to the total light passing the blue 
screen, the red screen, the yellow-green screen was found on February 15 to be 85'5, 
35'4, 0, 0'5 or 100, 41'4, 0, 0'55 ; on February 17 : 117'0, 45, 0, 0'5 or 100, 38\5, 0, 
