We determined temperature scanning thermograms of glycerol, with the same scanning rate for cooling and warming cycles by using an ultra-sensitive calorimeter at the scanning rate beta from 0.05 to 4 mK/s. Four peaks were observed during the warming process starting from below the glass transition temperature T'(g); glass transition, crystallization, solid-solid phase transition, and melting. T'(g) and the crystallization temperature T-p depends on beta with Arrhenius relation. A broad melting behavior was obtained in a temperature range larger than 10 K, which suggests that structural distribution exists in the crystal. The solid-solid phase transition at 229.1 K was discovered. (c) 2011 Elsevier B.V. All rights reserved.