ABSTRACT
Pycnometers are essentially flasks whose internal capacity has been determined by weighing the vessel empty and again when filled with water. The pycnometer can then be filled with a liquid of unknown density and, from a similar set of weighings, the unknown density of the liquid is determined by dividing the mass of the liquid by the internal capacity of the pycnometer. The pycnometer is fabricated from borosilicate glass with a linear coefficient of thermal expansion of 0.0000033/°C. The constant-temperature water bath was set to a temperature very close to 25°C, the reference temperature for the pycnometer. A two-probe thermistor thermometer with a standard uncertainty of 0.003°C was used to measure the water temperature in the bath. The thermometer probes were inserted into the space between the wall of the brass sleeve and the pycnometer body. There are three parameter measurements required to calculate the air density: air temperature, barometric presssure, and relative humidity.
