The Effect of Pressure on Diffusion in Liquid Sulfur

Diffusion coefficients have been measured in liquid sulfur to 2500 atmospheres pressure for isotherms at 140°C, 150°C, 175°C, and 210°C. One isotherm was also obtained at 195°C for sulfur containing 0.75 percent iodine. The motion in the viscous region is characterized by very small activation volumes which indicates that the moving segment is very small. This shows why the drop in diffusion rate in the transition region is small compared with the increase in viscosity. The iodine reduces the ``effective temperature'' 10–15°C. Above 1200–1500 atmospheres only one form of liquid sulfur seems to exist.