Hydrometer

Hydrometer is an instrument used to measure the specific gravity (or relative density) of liquids; that is, the ratio of the density of the liquid to the density of water.

Description

A hydrometer is usually made of glass and consists of a cylindrical stem and a bulb weighted with mercury or lead shot to make it float upright. The liquid to test is poured into a tall container, often a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer correlates to specific gravity.

Uses

Hydrometers are used by winemakers, beer brewers, honey mead brewers, and saltwater aquarium enthusiasts, among others. They are used to determine the amount of sugar in a solution, which can be useful in calculating potential alcohol content, or to measure the salinity of water.

Types of Hydrometers

There are several types of hydrometers used in different industries. These include:

• Saccharometer - A saccharometer is a type of hydrometer used for measuring the sugar content in a solution. It is commonly used in wine and beer making.
• Salinometer - A salinometer is a type of hydrometer used for measuring the salt content in a solution. It is commonly used in saltwater aquariums and marine biology.
• Lactometer - A lactometer is a type of hydrometer used for measuring the purity of milk. It measures the density of milk compared to water.

See Also

• Density
• Specific gravity
• Saccharometer
• Salinometer
• Lactometer

References

• 
  Diagram of an Areometer
• 
  Measuring brine concentration with a hydrometer
• Saccharometer at the Merseyside Maritime Museum
  Saccharometer at the Merseyside Maritime Museum