Measurements of both A→B and B→A transitions have been made as a function of magnetic field up to ∼100 G at temperatures and pressures close to the polycritical point (PCP). Forms for the specific heat differenceCA−CB=C0(P)−α(P)(Tc−T)/Tc and for the magnetization differenceMA−MB=βH(Tc−T)/Tc fit the data satisfactorily except very nearTc, where some other mechanism, thought to be a free energy difference due to residual heat flows, tends to stabilize the A phase. The pressure of the PCP, taken to be that at whichC0=0, is found to be 21.22±0.02 bar.