A New Negative Carbon for Low-Amperage High-Intensity Trims

Abstract

A new negative carbon is described which makes possible the extension to low current and short arc length of the high-intensity direct-current carbon arc with copper-coated non-rotating electrodes. Data are given which show that this new negative carbon, known as the “Orotip” C carbon, has made feasible combinations of carbons and burning conditions which bring about significant improvements in the efficiency of production of light from the standpoint of carbon utilization and power consumption. This new negative carbon has practically eliminated carbide tipping and its undesirable consequences. Results are given which show that most of the theaters now using low-intensity carbon arcs have an inadequate level of screen brightness. It is shown that the new combinations made possible by the “Orotip” C negative carbon offer a remedy for this, while at the same time giving a better color quality and maintaining a total operating cost no higher, or only slightly higher, than for the low-intensity combination.