Doiron, T; Behringer, RP; Meyer, H, *Equation of state of a*^{3}He-^{4}He mixture near its liquid-vapor critical point,
Journal of Low Temperature Physics, vol. 24 no. 3-4
(1976),
pp. 345-363 [doi] .
**Abstract:**

*Measurements of the pressure coefficient (∂P/∂T)ρ,x are reported for a3He-4He mixture with a mole fraction X=0.805 of3He in the neighborhood of the liquid-vapor critical point. These include data on 16 isochores taken over the density interval -0.5≤Δρ≤0.5 and over the temperature range -0.1 ≤t≤0.1, where Δρ=(ρ-ρc)/ρc and t=(T-Tc)/Tc,with ρc and Tc,respectively, the critical density and temperature of the mixture. From the discontinuity of (∂P/∂T)ρ,x at the boundary between the two-phase and the one-phase regions we determine the dew-bubble curve near Tcwith better precision than was done in recent PVT experiments. From the extrapolation of data not approaching Tccloser than 1 mK, (∂P/∂T)ρ,x along the critical isochore appears to be discontinuous at Tc,while for the isochore ρ/ρc≃0.92, (∂P/∂T)ρ,x is continuous across the dew curve. It is found that this latter isochore cuts the dew curve at its highest temperature. These observations are discussed in terms of general thermodynamic arguments and theoretical predictions of the asymptotic behavior. We calculate (∂P/∂T)ρ,x from the scaling equation of state proposed by Leung and Griffiths for3He-4He mixtures, using their numerical parameters. In spite of some systematic deviations, especially in the two-phase region, there is in general good agreement with experimental results. In particular, the shape of the measured dew-bubble curve and the apparent discontinuity of (∂P/∂T)ρ,x along the critical isochore show excellent agreement with theory. © 1976 Plenum Publishing Corporation.*