higanyoszlop

A higanyoszlop, or mercury column, refers to a vertical column of liquid mercury contained in a narrow glass tube or cavity and used as the sensing element in several measurement devices. Mercury’s high density, very low vapor pressure, and relatively predictable thermal expansion make a thin column a compact and precise indicator of pressure or temperature.

In barometers, the atmospheric pressure is supported by a mercury column inside a tall sealed tube open at the bottom to the atmosphere. The height of the column, measured in millimetres of mercury (mmHg), varies with weather. At sea level, standard atmospheric pressure is about 760 mmHg. The term torr, used in some pressure measurements, derives from this relationship.

Mercury thermometers rely on the expansion and contraction of mercury in a capillary as temperature changes. The vertical movement of the mercury column within a narrow bore is read on a calibrated scale to determine temperature. Mercury thermometers were widely used due to their uniform expansion, but they have declined in favor of non-mercury or electronic devices because of toxicity concerns.

Mercury column manometers are used to measure pressure differences in gases and fluids. A mercury column balances the unknown pressure against a reference pressure, and the resulting height difference in the column is read from a scale.

Construction typically involves a sealed glass tube with a reservoir of mercury at one end, leaving a vacuum or low-pressure space above the column. Safety is a major consideration, as mercury is toxic and can vaporize under certain conditions. Spills require careful handling and proper containment.

Historically, the higanyoszlop has played a central role in precise measurement and instrumentation, notably in barometry and thermometry, but its use has declined in many applications due to toxicity and environmental concerns.