DR. MEYER WILDERMAN ON CHEMICAL DYNAMICS 
356 
when the nipples have pinholes of only 15 or 20 candle power each. The clear 
circular flame so obtained consists of lines interrupted by narrow air spaces. Having 
all twelve lines in a narrow circle of only 1 or 1-j inch diameter, at equal distances 
from one another, the direction of all the flames perpendicular, and the flames of 
equal length, though, perhaps, of not quite the same thickness, we can safely assume 
that the light comes from a perpendicular line drawn through a point near the centre 
of the narrow circle. 
Since the error arising - from small variations in the thickness of the lines cannot 
possibly in this case be greater than 1-2 millims. in the distance, this can, for the 
distance we have to use (| to 2 metres), be completely neglected. The variations 
in intensity in the line of the flame proved to be due chiefly to variations in its top; 
by means of the chimney y, all the top parts of the line-flames are cut off. Owing 
to the draught the lines are straightened and the air supply increased, while the 
products of combustion are removed and a clear white flame, remarkable for its 
constancy and brilliancy, is obtained. The screen and chimney y can be moved 
higher or lower by means of the screw d, so as to get not only a constant flame with 
the photometer, but a flame of the desired intensity, the rest of the adjustment of 
the intensity being produced by means of the regulating tap. Besides the upper 
part of the flame, the lower part was also cut out by means of an adjustable short 
cylinder, which was also water-jacketed and connected with the water jacket of the 
burner. 
Thus, with the simple arrangements described (generator, balance governor and 
burner), a source of light of 200-250 candle power (or 500 candle power and more, 
according to the number of nipples employed) can be obtained, which will remain 
constant, within l or 2 per cent., for a considerable time without regulation or 
adjustmentA By means of the regulating tap and measuring instruments, the 
intensity of the light can be adjusted with an accuracy to 0T per cent., and even 
much less. 
The General Arrangements used for the Measurement and Adjustment 
of tee Intensity of the Acetylene Light. 
The Principle of the Method. Acetylene as a Universal Standard from 
0 - I or 1 to 500 or 1000 Candle Power. 
The light of the acetylene burner, which is placed at a certain distance from the 
thermopile, is allowed to fall on the exposed junctions of the Rubens thermopile 
(with 40 iron-constantan junctions), which is connected with galvanometer. A 
second measurement is made directly after by means of a Clark cell and standard 
* It should be noted that with the increase of the candle power of the burner, a greater pressure of the 
gas (in the gas-holder, &c.) is necessary for getting the best conditions for the liame. 
