The densimeter was also equipped with
internal thermostat with two platinum thermometers (Pt 100).
The temperature reproducibility (standard deviation) was equal
to 0.01 K. Before every measurement the densimeter was calibrated
with double distilled water and dry air. The mixture under
investigation was preheated to several degrees higher than measurement
temperature to avoid formation of gas micro-bubbles
in the solvents. The density of every mixture was measured for
several times. The reproducibility (standard deviation) of density
values was 0.00001 g/cm3. The density measurements were carried
out at five temperatures – 278.15, 288.15, 298.15, 308.15, and
323.15 K. At 278.15, 288.15, and 298.15 K the density of {water
(1) + tert-butanol (2)} mixture was measured not over the entire
composition range because of the mixture freezing. The maximum
uncertainty of temperature measurement during density determining
did not exceed 0.03 K. The total accuracy of density measurement
did not exceed 0.00005 g/cm3. The procedure was
defined in details earlier