areometer

[In Ger. areometer; Fr. aréomètre; Port. a reo metro; from Gr. ἀραιός (araios) = (1) thin, (2) porous, and μέτρον (metron) a measure.) An instrument designed to measure the specific gravity of liquids. The simpler areometers measure only the relative weights of liquids. They consist of a tube of gla , terminated in a ball at its lower part, and divided into equal portions through its whole length. Another ball filled with mercury is soldered below to keep it vertical. The depth to which it sinks in various líquids is in the inverse ratio of their relative specific gravities. In Fahrenheit's areometer there is an adjustment by weights, so that the AREOMETER. volume of the part immersed is constant, and thus the absolute specific gravity of the liquid tested is ascertained, that of water being previously fixed. (Glo og. Nov., .)