Abstract
To establish temperature scales for columbium, thorium, rhodium and molybdenum spectral emissivities were measured for these metals at λ=0.667μ. The Mendenhall V wedge was used for columbium and rolled cylinders were used for the other metals. Rolled cylinders were more satisfactory for measuring emissivities than specimens in other forms. Rigorous heat treatment was found necessary for accurate results. Emissivities for all four metals were constant with temperatures. Results are: