Deluc's analysis came to the conclusion that mercury-based thermometers were the best for practical use: He made an experiment, as follows: Suppose there are two amounts of water, say one liter, are mixed. The two amounts have different temperatures. The temperature of both liquids are taken, before the mix, and the temperature of the mix is measured. The mix should have the temperature that is the mean of both temperatures. This relationship only held reliably, when mercury was used in thermometers. From the late 18th century, almost all thermometers used mercury, for this reason. Thermometers that use other substances than ethanol but have 80 scales between the boiling and the freezing points of water have nothing in common with Réaumur's thermometer, except for the name.