The variation of iinterfacial tension with temperature of two different systems, water-oil (liquid paraffin, C18H38, solution of solid paraffin)and silicone oil-vegetable oil was determined and the factors that influence the variation of the shape of the relation curves were examined.It is found that the presence of minute amount of surface active impurity was the main cause of the shape variation of the relation curves. The shape variation was eliminated by adsorptive agent.Therefore, it is important to insure purity of the experimental system in order to obtain reliable results on the study of thermocapillary flow caused by interfacial tension.
