The rise of an unsupported liquid column through the air from a quiescent pool to a capillary with suction (the “ductless siphon”) is interpreted approximately in terms of the elongational viscosity(η̄)of several solvents and dilute polymer solutions. The maximum height of siphon rise(h*)is used to characterize the ratioη̄/η,where η is shear viscosity, and an approximate hydrodynamic analysis showsη̄/η∼(h*)2.Measurements made for polyisobutylenes in toluene and jet fuel (kerosene), for a proprietary antimisting agent PX in jet fuel, and for polyethylene oxide and polyacrylamides in water show thath*depends on molecular variables as predicted by dilute‐solution theories forη̄/η.Polymer molecular weight range is0.8×106