Melting curves of argon and methane

The melting curves of argon and of methane have been measured in a diamond-anvil cell from 290 to>700 K. Measurements of argon, fit to the equation P−6.9×10−5=0.244[(T/83.805)1.476−1], are in excellent agreement with previously published values up to a temperature of ∼ 500 K and thereafter diverge slowly. Measurements of methane, fit to P−1.17×10−5=0.208[(T/90.6941)1.698−1], are in serious disagreement with the only previous studies to extend past 400 K.