Many medical therapies require liquid plugs to be instilled into and delivered throughout the pulmonary airways. Improving these treatments requires a better understanding of how liquid distributes throughout these airways. In this study, gravitational and surface mechanisms determining the distribution of instilled liquids are examined experimentally using a bench-top model of a symmetrically bifurcating airway. A liquid plug was instilled into the parent tube and driven through the bifurcation by a syringe pump. The effect of gravity was adjusted by changing the roll angle and pitch angle of the bifurcation ( was isogravitational). determines the relative gravitational orientation of the two daughter tubes: when , one daughter tube was lower (gravitationally favored) compared to the other. determines the component of gravity acting along the axial direction of the parent tube: when , a nonzero component of gravity acts along the axial direction of the parent tube. A splitting ratio , is defined as the ratio of the liquid volume in the upper daughter to the lower just after plug splitting. We measured the splitting ratio, , as a function of: the parent-tube capillary number ; the Bond number (Bo); ; ; and the presence of pre-existing plugs initially blocking either daughter tube. A critical capillary number was found to exist below which no liquid entered the upper daughter , and above which increased and leveled off with . increased while decreased with increasing , , and Bo for blocked and unblocked cases at a given . Compared to the nonblockage cases, decreased (increased) at a given while increased (decreased) with an upper (lower) liquid blockage. More liquid entered the unblocked daughter with a blockage in one daughter tube, and this effect was larger with larger gravity effect. A simple theoretical model that predicts and is in qualitative agreement with the experiments over a wide range of parameters.