Acquarzente (literally, "burning water") is the Accademia del Cimento's term for wine spirit, i.e., alcohol. It was used as a thermometric liquid instead of water. "There are two reasons for using acquarzente rather than natural water in these instruments. First, it is more sensitive, i.e., it responds faster than water to the slightest changes in cold and heat, and, as it is quicker to incorporate those changes, it moves instantly because of its very light weight. Second, natural water—however noble and pure—inevitably deposits, sooner or later, some residue or scum that gradually stains the crystal and makes it less transparent. By contrast, the very subtle spirit of wine, which we call acquarzente, is always pristine, never losing its characteristic fine clarity" (Saggi di naturali esperienze, Florence, 1667).