Compression and Densities of Four Solidified Hydrocarbons and Carbon Tetrafluoride at 77°K

The piston displacement method of Bridgman has been used to measure the volume changes and compressibilities of solid ethane, ethylene, propane, propylene, and carbon tetrafluoride from 0 to 20 000 kg/cm2 at 77°K. The only polymorphic phase change observed is a first‐order transition at P = 180±80 kg/cm2 at 77° in CF4. The densities of these solidified gases at 77° have been measured at atmospheric pressure by direct condensation into a volumetric flask. The accompanying pressure drop in a storage tank of known volume is observed.