  Based on simultaneous observations of solar flares in hard and soft X-rays we
studied several aspects of the Neupert effect. About half of 1114 analyzed
events show a timing behavior consistent with the Neupert effect. For these
events, a high correlation between the soft X-ray peak flux and the hard X-ray
fluence is obtained, being indicative of electron-beam-driven evaporation.
However, for about one fourth of the events there is strong evidence for an
additional heating agent other than electron beams. We discuss the relevance of
these findings with respect to Parker's idea of coronal heating by nanoflares.
