Measured data for CH4 I from:
Armstrong, G.T., F. Brickwedde, and R. Scott 1955.  Vapor pressures of the methanes.  J. Res. Natl. Bureau Standards 55, 39-52.
T(K)     P(bar)
51.00   5.61e-06
52.00   8.63e-06
53.00   1.31e-05
54.00   1.95e-05
55.00   2.87e-05
56.00   4.16e-05
57.00   5.97e-05
58.00   8.45e-05
59.00   1.18e-04
60.00   1.64e-04
61.00   2.25e-04
62.00   3.05e-04
63.00   4.10e-04
64.00   5.46e-04
65.00   7.22e-04
66.00   9.45e-04
67.00   1.23e-03
68.00   1.59e-03
69.00   2.03e-03
70.00   2.58e-03
71.00   3.27e-03
72.00   4.10e-03
73.00   5.12e-03
74.00   6.35e-03
75.00   7.84e-03
76.00   9.62e-03
77.00   1.18e-02
78.00   1.43e-02
79.00   1.73e-02
80.00   2.08e-02
81.00   2.49e-02
82.00   2.97e-02
83.00   3.53e-02
84.00   4.17e-02
85.00   4.92e-02
86.00   5.78e-02
87.00   6.76e-02
88.00   7.88e-02
89.00   9.16e-02
90.00   1.06e-01
