Coalescence has been widely studied in surfactant solutions. Nevertheless, a quantitative prediction of the lifetimes of liquid films stabilised by surfactants is still lacking due to intricate couplings between the flow and concentration fields as well as the disjoining pressure. Complexity arises from the timescales of surface and bulk transfers of surfactants. >Hence, the situation for surfactant solutions is so intricate that predicting the lifetime of a soap film remains a challenge. We have identified a very simple system in which it is possible to describe quantitatively the stability of liquid films. These are liquid mixtures, miscible in all proportions, for which: (i) disjoining pressure is always attractive and independent of local composition, (ii) surface/volume transfers are only controlled by diffusion, (iii) film lifetimes vary from 1ms to 10 s by changing the composition. Consequently, the question of coalescence and its consequences on diphasic flows is well posed in these systems. The purpose of the internship is to describe the physical mechanisms acting to stabilize foams of two mixed liquids. We will perform experiments on suspended liquid films thanks to a specially designed cell. We will explore the effects of the curvature which sets the capillary pressure gradients and the drainage time. These experiments will be analyzed and compared to on-going numerical simulations to improve our understanding of the stabilizing mechanisms in oil foams.