Relative density
A pycnometer (from Greek: πυκνός (puknos) meaning "dense"), also called pyknometer or specific gravity bottle, is a device used to determine the density of a liquid. A pycnometer is usually made of glass, with a close-fitting ground glass stopper with a capillary tube through it, so that air bubbles may escape from the apparatus. This device enables a liquid's density to be measured accurately by reference to an appropriate working fluid, such as water or mercury, using an analytical balance.
Methanol (data page)
Here is a similar formula from the 67th edition of the CRC handbook. Note that the form of this formula as given is a fit to the Clausius–Clapeyron equation, which is a good theoretical starting point for calculating saturation vapor pressures:
Data obtained from "Lange's Handbook of Chemistry", 10th ed. and "CRC Handbook of Chemistry and Physics" 44th ed. The annotation, "d a"°C/"b"°C, indicates density of solution at temperature "a" divided by density of pure water at temperature "b" known as specific gravity. When temperature "b" is 4 °C, density of water is 0.999972 g/mL.Except where noted otherwise, data relate to standard ambient temperature and pressure.