Aerometer

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It has been suggested that this article or section be merged into hydrometer. (Discuss)

An aerometer, created by Jacques Alexandre César Charles, is a scientific instrument used to measure the weight and density of a gas or liquid. It is a hollow tube, widened at the bottom where a weight is placed (B). A scale is present on the upper part of the rod. The aerometer is placed in the liquid needing to be tested. The scale (A) will be held upright by the weight in the lower part (B). The density of the liquid is read where the scale penetrates the surface of the liquid.

[edit] Scope of use

Different solutes may add or subtract density, as the density of a liquid is only partly determined by the density of the solvent, so the aerometer is of no use in determining the nature of an unknown liquid. The apparatus can monitor a process or estimate a concentration of solutes. For example, one can determine the alcohol contents of a beverage after distillation by using the aerometer.

[edit] Principle

The aerometer is an example of the law of Archimedes: the upward force by a liquid equals the mass of the displaced liquid. The weight of the aerometer is fixed; the deeper the meter sinks in the liquid, the more it is replaced. The aerometer floats when equilibrium is reached.