The normal spectral emittance (λ = 0.645Jμ) was determined for vanadium between 1100 and 1750 K and for tantalum between 1200
and 2600 K, at pressures below 10
-6 mm Hg for elec-trochemically and mechanically polished surfaces. The emittance was found to decrease with increase in temperature.
It was also lower for the electrochemically polished surface. An empirical equation was fitted to the experimental data, and
it was used to predict the emittances up to the melting points.
Formerly a National Science Foundation Presidential Intern and Ames Laboratory-USAEC Postdoctoral Fellow, Iowa State University,
Ames, Iowa, 50010