Experiments using an optically polished Pyrex disk and aqueous dodecylammon
ium acetate (DAA) films showed that the velocity with which the films reced
e increases markedly if the runs are repeated at short time intervals, wher
e equilibrium cannot be reattained. This results from DAA molecules being d
esorbed from the disappearing liquid-air interface and being deposited on t
he solid-air interface being formed. Controlled experiments with Pyrex part
icles in a modified Hallimond tube showed a similar increase in flotation r
ate, again due to excess adsorption of DAA molecules that were transferred
to the solid-air interface from the bubble on contact.