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Contact angle measurements for the air/water/polyethylene and for the oil/water/quartz systems have been carried out over a wide range of drop (bubble) sizes, from 60 μm to 2 mm. Two distinctly different experimental techniques were used: placement of the drop (bubble) with a microsyringe, the static technique, and collision of the drop (bubble) with the surface due to the buoyant force, the dynamic technique. A nonlinear relationship between the cosine of the contact angle measured through the aqueous phase (cos θ) and the reciprocal radius of the drop base (1/r) was obtained. The lack of linearity for this range of drop sizes cannot be attributed to a variation in line tension which should be constant. Nevertheless, a pseudo line tension can be calculated and it was found that negative pseudo line tensions on the order of -1 × 10^-8 N(-1.2 × 10^-8 -6.6 × 10^-8 N) were obtained for small drops or bubbles (drop …