Fuente: WIPO "milk" The device of the invention comprises; a contact column 1 A in which a test liquid flows from top to bottom and a vapor flows from bottom to top, a rotary shaft 9 which is inserted vertically in the contact column 1 A, rotors 10 which are provided at different heights on the shaft, and which convert the test liquid into a thin film by centrifugal force and then discharge the test liquid from the outer periphery thereof, and trays 20 which receive the test liquid discharged from an upper rotor and guide the test liquid to the center of a lower rotor. The rotors 10 have furrows 13, which the test liquid flows over when the filmy test liquid flows out from the center of the rotor towards the outer periphery.