The heat of fusion was reported as 7.9 * 0.5 kcal. mole-' with a heat of sublimation of 96.6 A 0.5 kcal. mole.-' Inasmuch as the deviation from linearity may alternatively be accounted for by assuming a reasonable AC, for the sublimation process and as the reported melting points are rather lower than would be expected from com- parison with other fluorides] we have undertaken a determination of the plutonium trifluoride melting point in the apparatus shown in Fig. 1. .An inconclusive ...