A SURFACE-TENSION FOR MISCIBLE FLUIDS

Some experiments suggest that large gradient of concentration at the ' 'interface'' between two miscible liquids with small coefficient of mo lecular diffusion, generates an ''equivalent'' surface tension similar to that between immiscible fluids. This equivalent tension vanishes w ith time. Its value has been indirectly deduced from the experiment of viscous displacement between water and glycerine. It is here directly measured by the rotating drop method.