Table 2. Summary of reanalysis of Keller’s gaseous He³ isotherms [12].

The isotherm designations, the data points, and the method of normalization for each isotherm are the same as those used by Keller. ${\overline{P}}_4$ is the average He⁴ vapor pressure for each isotherm and ${\overline{P}}_3$ is_the average He³ vapor pressure for the α isotherm. $T_{58}({\overline{P}}_4)$ is the normalized temperature for each isotherm and is the 1958 He⁴ Scale temperature corresponding to ${\overline{P}}_4$. $P_3({\overline{P}}_4)$ is the directly interpolated He³ vapor pressure corresponding to ${\overline{P}}_4$, using the direct interpolation equations described in Part I, and $T_{62}[P_3({\overline{P}}_4)]$ is the 1962 He³ Scale temperature corresponding to $P_3({\overline{P}}_4)$. The values of T_iso, B, and C listed under the heading “Three-constant fit” were obtained by solving eq (9) using Deming’s method of least squares adjustment with errors in two measured variables (see appendix A). The standard errors and the weighted variance are calculated in accordance with the statistical formulas given by Deming [47]. The two constant fit values of T_iso and B were obtained by solving eq (9) assuming C=0. For the For the γ, δ, and ϵ isotherms the variance of the three-constant fit is lower and the values of C are greater than the magnitude of their statistically assigned errors. Therefore the three constant fit solutions were used for fitting He³ virial coefficient equations, eqs (10) and (11), and for the temperature differences shown in figure 2 of Part II.

Isotherm	Units	γ	δ	α	ϵ	β
No.of points		18	18	11	10	8
${\overline{P}}_4$	mm Hg	489.52	178. 09	36.16	13.070	3.782
T58(${\overline{P}}_4$)	mdeg	3779.1	2985.3	2154.2	1813.4	1510.3
P3(${\overline{P}}_4$)	mm Hg		607. 70	197.43	105.33	52.21
${\overline{P}}_3$	mm Hg			197.62
T62[P3(${\overline{P}}_4$)]	mdeg		2985. 2±0.2	2154.4±0.2	1813.1±0.2	1510.2±0.2
T62(${\overline{P}}_3$)	mdeg			2.1550
THREE-CONSTANT FIT
Tiso-	mdeg	3782.3 ±2.2	2992.4±1.6	2153.7±1.0	1816.4±0.8	1510.4±2.5
B-	cm3/mole	−65.50±0.86	−86.31 ±0.52	−118.81 ±1.35	−145. 08±1.61	−162.15±10. 7
C-	cm6/mole2	1192 ±306	1746±136	548±822	2611 ±1289	−11,069±16, 390
Variance		7.0	13.8	6.1	0. 86	4.8
(T58–Tiso)	mdeg	−3.3±2.2	−7.1±1.6	0.5±1.0	−3. 0±0.8	−0.1 ±2. 5
(T62–Tiso)-	mdeg		−7.2±1.8	0.7±1.2	−3.2±1.0	−0.2±2.7
(T62(${\overline{P}}_3$)–Tiso)	mdeg			1.3±1. 0
TWO-CONSTANT FIT
Tiso-	mdeg	3774.4±1.3	2974.4±2.8	2153.2±0.6	1814. 9±0.4	1512.0±0. 7
B-	cm3/mole	−62.18±0.19	−79.66±0.33	−117.92 ±0.26	−141.87 ±0.29	−169.30±1.15
Variance-		13.2	156	5.7	1.20	4.4