A high resolution a.c. and relaxation calorimetric study has been carried out on heptyloxybenzylidene butylaniline (7O.4) in two silica aerogels with mass densities rho 0.08 and 0.17g cm -3. Bulk 7O.4 exhibits strongly first order N-I, N-SA and SC-CrG transitions as well as a mean-field second order SA-SC transition. The 7O.4/aerogel samples exhibit three first order transitions (N-I, N-SA, SA-crystal) that are appreciably shifted and broadened relative to bulk 7O.4. The SA-SC transition is not observed in either of the aerogel samples.