360 DR. MEYER WILDERMAN ON THE CHEMICAL STATICS AND DYNAMICS OF 
On the 4th and 5th of June we got practically the same deflection (18 and 17 millims.). 
On the 6th and 8th of June we got with the new carbons 28 millims., and the same 
result was obtained with the same carbons several days later, on the 11th of June. 
When corrected for the same intensity of light, A/B = 0'586, we still get for the 6th, 
8th, 11th of June the values 25'6, 24J, 25'2 millims. instead of 18, 17 millims. of the 
4th and 5th of June. Thus the composition of light, not only the intensity of the 
light, changes with different carbons used. It makes also a further investigation 
necessary, whether a small oxidation of the Ag plates, or change in their brightness 
which may take place in time, may also influence the values of the E.M.F.’s obtained. 
Plate of June 11, 1903 (6 Curves ), W6, Plate I. 
The same system from June 3. The circuit was always kept closed between the 
experiments of the different days, and the same plate was always exposed to light. 
The E.M.F. in the dark = 27 centims. = 26 - 9 x 10“ 6 volt. Experimental data, 
Plate N6, Table I., pp. 390-391. Distance of the arc from quartz vessel 36 (37) centims. 
The carbons the same as on the 6th and 8th of June. 
Curve Nl obtained with the total white light gave = 32 millims. deflection 
= 37'5 x 10 -9 ampere = 31’9 x 10 -6 volt. Corrected for the thermo E.M.F., the 
deflection at a constant temperature = 32 millims. — (1‘9 to 3 millims.) = 29 to 30'1 
millims. Curve N2 was obtained with the blue gelatine screen; the deflection in 
light = 15 millims. = 17‘6 x 10“ 9 ampere = 14'5 x 10 -6 volt. Corrected for the 
thermo E.M.F., the deflection =15 millims. — (P3 to 2 millims.) = 13 to 137 millims. 
Curves N3 and N3 l5 obtained with the green-yellow gelatine screen, gave 2’5 millims. 
and 2'5 millims. = average 2‘5 millims. deflection = 2'9 x 10 -9 ampere = 2'4 x 10 -h 
volt. Corrected for the thermo E.M.F., the deflection = 2'5 millims. — (1*3 to 1'9 
millims.), i.e., no E.M.F. at a constant temperature can be shown to be produced by 
light. Curves N4 and N4 l5 obtained with the red gelatine screen, gave 2 millims. 
and 1'5 millims. = average 175 millims. deflection = 27 x 10 -9 ampere = 1 '8 x 10 -b 
volt. Corrected for the thermo E.M.F., the deflection= 1'8 millims. — (1 *4 to 2T 
millims.), i.e., no E.M.F. at a constant temperature can be shown to be produced 
by light. 
From the above it is to be seen that the E.M.F. produced by light at a constant 
temperature is principally due to the blue rays of the spectrum and very little to 
the red or yellow parts of the same. (The results obtained with the gelatine screens 
contain no correction for the gelatine.) 
In § 2 it has been shown that the thermo E.M.F. caused by the total light forms 
about 6 to 9 per cent, of the total E.M.F. 
An application of a correction of 9 per cent, for the heat effect of total light gives 
the following results for the law of light intensity at a constant temperature: — 
