Specific gravity is a measure of the density of a substance relative to the density of water. A higher specific gravity indicates a denser substance. There are a few different ways to check the specific gravity of a substance, but the most common method is to use a hydrometer. A hydrometer is a graduated glass or plastic cylinder with a weighted bulb at the bottom. When the hydrometer is placed in a liquid, it will float at a level that is proportional to the density of the liquid. The specific gravity of the liquid can then be read from the scale on the hydrometer.
Specific gravity is an important property of liquids because it can be used to determine the concentration of a solution. For example, the specific gravity of a sugar solution will increase as the concentration of sugar in the solution increases. Specific gravity can also be used to identify different liquids. For example, the specific gravity of water is 1.000, while the specific gravity of gasoline is about 0.700.