Measurements have been made of far-infrared absorption in pure, face-centered cubic, superconducting lanthanum at 1.3°K. The results indicate a gap width 2∆=12.0+/-1.0 cm-1. In terms of the measured value of the critical temperature, Tc=6.06°K, 2∆=2.85+/-0.24 kTc. The data indicate the possible presence of a small amount of structure in the absorption curve at an energy about twice the gap width. These results are compared with theoretical predictions which have been made recently from a proposed new mechanism for superconductivity in lanthanum.