An apparatus for accurate measurement of liquid densities over an extended temperature range

An apparatus for accurate measurement of liquid densities, based on the second of two designs due to Beams and Clarke, is described. The sealed sample cell contains a glass float, which can be held magnetically in the midst of the liquid sample by a servo-controlled solenoid. The sample cell is suspended from a conventional balance and weighed with and without activation of the solenoid. Pure water is used to standardize the apparatus. Advantages of the method are listed, and specific design features discussed. The present equipment is used to measure densities from 0·7 to 2·9 g cm −3 at temperatures from 20 to 150°C and pressures up to 700 kN m −2 . An estimated accuracy to ±50 p.p.m. is attained with a sample of volume 6 cm 3 . The results of measurements on benzene and hexafluorobenzene are presented.