Kviksølvbarometret

Kviksølvbarometret, or mercury barometer in English, is an instrument used to measure atmospheric pressure. Invented by Evangelista Torricelli in the 17th century, it works on the principle of balancing the weight of the atmosphere against a column of mercury. A typical mercury barometer consists of a glass tube sealed at one end and filled with mercury. This filled tube is then inverted into a reservoir of mercury.

The atmospheric pressure outside the reservoir pushes down on the surface of the mercury, causing a column of mercury to rise in the inverted tube. The height of this mercury column is directly proportional to the atmospheric pressure. At standard atmospheric pressure at sea level, the mercury column typically stands at about 760 millimeters or 29.92 inches. Measurements are often expressed in units such as millimeters of mercury (mmHg), inches of mercury (inHg), or hectopascals (hPa).

Mercury barometers were widely used for weather forecasting and scientific research due to their accuracy and simplicity. However, concerns about the toxicity of mercury have led to their gradual replacement by aneroid barometers and digital barometers in many applications. Despite this, mercury barometers are still sometimes used in educational settings and by enthusiasts for their historical significance and direct demonstration of physical principles. Calibration and careful handling are essential for accurate readings and to prevent mercury spills.