346 DR. MEYER WILDERMAN ON THE CHEMICAL STATICS AND DYNAMICS OF 
§ 4. The Method of Investigation. General Arrangements of the Experiments. 
The general arrangements of the experiments are given in the following diagram 
On the right are the arrangements for a constant source of light : acetylene 
or the arc was used. AB is the acetylene burner. Acetylene from the generator 
passes through a balance governor, regulating tap, water manometer, drying apparatus 
to the specially constructed burner, as described in my previous publications. 
The arrangement of the arc 1 ight is as follows :—The current from the accumu- 
lators (Acc) passes through a resistance FI (Fleming) of 3 ohms, the arc (Ar), and 
the amperemeter (A); the voltmeter (V) is connected either with the terminals of 
the Dubose arc, or, since the resistance is kept constant, at the terminals of the 
accumulators where the voltage was much higher (67 volts instead of 42), to get 
more sensitive reading. 
The light passes to a Rubens thermopile (RTh). The wooden screen (Scr) is 
placed between the Rubens thermopile and the source of light. The leads from the 
Rubens thermopile pass to the interrupter (E ; ) and reversing key (rk,), thence to a 
Nalder galvanometer N2. The incandescent Swan lamp (SwNl) throws a spot of 
light upon Nalder N2, which falls upon a transparent celluloid scale (Sc). When 
the screen is closed, the spot of light gives zero deflection and the reversing key 
gives the E.M. F. of the thermopile in the dark, if any; when the screen is opened, 
the deflection of the galvanometer read on the scale gives the intensity of light. 
This deflection was then calibrated in standard units. The Clark Nl is connected 
with the reversing key (rk y/ ), then with a standard 100,000 ohms manganin resistance 
(C), and the Nalder N2 is provided with a shunt D (10 ohms). The arrangements of 
the photometer are described in the former paper. The light also falls on the quartz 
window of the bath (B) (only one of the six quartz windows is open) and passes to 
the quartz vessel (QV) placed behind it at a distance of about 10 centims. The 
source of light is during the experiments placed at a suitable or desirable distance 
