  We consider the possibilities for prediction of liquids' density under
pressure basing on the inverse reduced fluctuations parameter, which is
directly connected with the isothermal compressibility. This quantity can be
determined basing on the thermodynamical properties of saturated liquid and it
consists of only two constant parameters within a relatively wide region close
to the melting points. It is confirmed by the comparison with the experimental
data on n-alkanes that the derived expression is a quite reasonable estimator
without a necessity to fit data along some parts of isotherms for different
temperatures. At the same time the obtained formula: i) can be reduced to the
form of the Tait equation and ii) the resulting Tait's parameters in this
representation have a clear physical meaning as functions of the excess
entropy, which determines the mentioned reduced fluctuations.
