Experiments with Arcs at Atmospheric Pressure

In the equation for the static characteristic of the electric arc at atmospheric pressure, $E=A+\frac{B}{I^n}$, the exponent $n$ has been interpreted by Nottingham and others as a constant independent of arc length and dependent linearly upon the boiling point of the anode material. This view is criticized from a consideration of new experimental data showing that the spread in measurements of $n$ is necessarily very large. The conclusion that "$n$ varies directly as the boiling point of the electrode (anode) material" is not given support by these experiments.