The IR spectra of he heavy metal fluoride glasses showed peaks at $1, 400cm^{-1}$ or $1, 100cm^{-1}$ due to metal oxyfluoride impurities. The intensity of this band and hence the oxide impurity content of the glass could be reduced considerably by the use of reactive atmosphere melting under $CCl_4$ In comparison with the fundamental IR absorption band of heavy metal oxides the oxide impurity bands observed in the heavy metal fluoride glasses are multiphonon bands due to a 2-phonon absorption process. The envelope of the a vs. v curve beyond thue fundamental region shows the exponential fall off of a with increasing v-typical of intrinsic multiphonon absorption. In the multiphonon region the amount of structure is intermediate between that observed for covalent solids and that for ionic solids.