Cars & Driving


  • An instrument which indicates the specific gravity, density, or a similar characteristic of a liquid. A hydrometer is usually simply placed in the liquid in question, and the depth it sinks is to correlated to its vertical scale.


  • A short stubby cylinder surmounted with a long graduated tube. The whole is sealed and weighted so that it floats upright in a liquid always displacing its own mass of liquid thus indicating by the depth to which it sinks the density or specific gravity of the liquid. Used for measuring alcohol, salt and sugar concentrations in solution.


  • noun an instrument which measures the density of a liquid


  • a measuring device used to measure the specific gravity of a liquid, comparing it to the density of pure water. This provides a measure of the sugar content of grape juice in the fermentation container. The instrument has a hollow cylindrical bulb with a lead weight in the bottom to make it float vertically and a number scale on the long stem that can be read as it floats in the liquid.