Nematic—smectic-A—smectic-Cend point: A volumetric study

Sensitive volumetric measurements show a classical second-order $A-C$ transition in mixtures of $\overline{8}S5$ with $\overline{7}S5$ in agreement with findings of Schantz and Johnson for pure $\overline{8}S5$, and apparently a first-order $A-N$ transition (although an extremely weak one) for 30 and 37 mole% of $\overline{7}S5$; thus an earlier suggestion of a (critical) end point where a second-order $A-C$ line meets the border of a first-order region, $N-A$ and then $N-C$, is corroborated.