Temperature of a Copper Arc

The temperature of a copper arc in air has been measured by comparing 31 sets of transition probabilities for spectra of 20 elements with spectral-line intensities from those elements separately added to the copper. The intensities are taken from the recently published NBS Tables of Spectral-line Intensities and the transition probabilities from the literature. The individual determinations are discussed. The set of determinations is shown to follow a Gaussian distribution about a mean of 5100 °K. The average deviation of the determinations is 470 °K and the standard deviation of the mean is 110 °K. This temperature may be used in the evaluation of thousands of atomic transition probabilities from the intensities in the new tables. The effect of the uncertainty in the temperature on derived transition probabilities is evaluated as a function of excitation potential.