The ancient philosophers regarded water as a basic element typifying all liquid substances. Scientists did not discard that view until the latter half of the 18th century. In 1781 the British chemist Henry Cavendish synthesized water by detonating a mixture of hydrogen and air. However, the results of his experiment s were not clearly interpreted until two years later, when the French chemist Antoine Laurent Lavoisier proved that water was not an element but a compound of oxygen and hydrogen.
Pure water is an odorless, tasteless liquid.
It has a bluish tint, which may be detected, however, only in layers of considerable depth. Supercooled water will freeze if it is disturbed, if the temperature is lowered further, or if an ice crystal or other particle is added to it. Its physical properties are used as standards to define the calorie and specific and latent heat and in the metric system for the original definition of the unit of mass , the gram . Because most substances are somewhat soluble in water, it is frequently called the universal solvent . Water combines with certain salts to form hydrates.