Figure 7.— Correction for He⁴ impurity, (T₆₂ —T_u), to be added to the uncorrected temperatures, T_u, calculated from the observed vapor pressure and the 1962 He³ Scale.

The correction is calculated as T₆₂—T_u=(1—X) (dlnP_x/dX)_T,X=1/(dlnP₃/dT) based on eqs (13) and (14) and using the derivative values listed in table 4. The curves can be used for ten times the indicated percent of He⁴ in the liquid if the ordinate is multiplied by ten.