Viscosities of Some Undercooled Liquid Alkyl Halides

The viscosities of i-butyl bromide, i-amyl bromide, and i-butyl chloride have been measured over a temperature range in which η changes from 102 poise to about 108 poise. The temperature dependence of η is very close to that of the dielectric relaxation time τ indicating the similarity of the molecular processes involved. This similarity thus appears to apply to ``nonassociated'' polar liquids as well as to hydrogen bonded liquids.