  Physical aging of glycerol following temperature jumps is studied by
dielectric spectroscopy at temperatures just below the glass transition
temperature. The data are analyzed using two single-parameter aging tests
developed by Hecksher et al. [J. Chem. Phys. 142, 241103 (2015)]. We generalize
these tests to include jumps ending at different temperatures. Moreover, four
times larger jumps than previously are studied. The single-parameter aging
tests are here for the first time applied to a hydrogen-bonded liquid. We
conclude that glycerol obeys single-parameter aging to a good approximation.
