The existence of nonisothermal transport of liquids through a gelatin membrane was first described by Lippmann in 1907, and 5 years later, it was investigated by Aubert in more detail using membranes of gelatin pig’s bladder, parchment paper and viscose. In this phenomenon, there is no liquid/vapor phase transition and it is known as thermo-osmosis (TO) or thermal osmosis (TO). Lippmann also observed TO in air, obviously without prior knowledge of the work of Feddersen and Reynolds. However, at that time the lack of theory on irreversible processes prevented the progress towards understanding this phenomenon.