  A special limit of an antiferromagnetic XYZ chain was recently shown to
exhibit interesting bulk as well as surface spin-flop transitions at T=0. Here
we provide a complete calculation of the thermodynamics of the bulk transition
using a transfer-matrix-renormalization-group (TMRG) method that addresses
directly the thermodynamic limit of quantum spin chains. We also shed some
light on certain spinwave anomalies at low temperature predicted earlier by
Johnson and Bonner.
