  We report quantitative experimental measurements of the Abraham force
associated with a propagating optical wave. We isolate this force using a
guided light wave undergoing an adiabatic mode transformation (AMT) along a
liquid-filled hollow optical fiber (HOF). Utilizing this light intensity
distribution within the liquid, we were able to generate a time-averaged
non-vanishing Abraham force density, while simultaneously suppressing the
Abraham-Minkowski force density. The incident laser field induced a linear
axial displacement of the air-liquid interface inside the HOF, which provided a
direct experimental measure of the Abraham force density. We find good
agreement between the experimental results and theoretical determinations of
the Abraham force density
