The ionization of the Kenelly-Heaviside layer was measured by Appleton's method during the total solar eclipse of August 31, 1932. In contrast to normal days, a sudden decrease of 58% during the period of optical totality was found. This is shown to be in accord with Appleton's, but not with Chapman's, theory that the cause of lower layer ionization is ultra-violet light from the sun. Some measurements were made of the effective height of the Appleton layer and these are discussed in detail. There is a marked effect at the time of optical totality on this layer also.