Based on previous works on polymers by Bauer et al. [Phys, Rev. B (2000)],
this paper describes a capacitative method for measuring the dynamical
expansion coefficient of a viscous liquid. Data are presented for the
glass-forming liquid tetramethyl tetraphenyl trisiloxane (DC704) in the
ultraviscous regime. Compared to the method of Bauer et al. the dynamical range
has been extended by making time-domain experiments and by making very small
and fast temperature steps. The modelling of the experiment presented in this
paper includes the situation where the capacitor is not full because the liquid
contracts when cooling from room temperature down to around the
glass-transition temperature, which is relevant when measuring on a molecular
liquid rather than polymer
