Instabilities in ternary diffusion

Two series of experiments on gaseous diffusion instabilities are reported. In one series the convection cells are made visible with ammonium chloride smoke; the observed behavior appears quite complex. In the other series the stability limits in osmotic diffusion are investigated as a function of pressure and composition for H2-CH4-CO2. Reasonable agreement is obtained with a stability theory based on Rayleigh's treatment of thermal convection.