Usage: Density meters are widely used. Those heavier than water are used to measure the density of various acid, base, and salt aqueous solutions, such as sulfuric acid, nitric acid, hydrochloric acid, and certain inorganic or organic acids. Those lighter than water are used to measure solutions such as methanol, ethanol, ether, as well as liquids like gasoline, kerosene, vegetable oil, and petroleum ether. For research and laboratory purposes when measuring the density of liquids, using a second-class standard density meter is more appropriate.