Mercury Thermometer

How to Find Your Best Mercury Thermometers

It is made up of the bulb containing mercury attached to a glass tube of diameter. The volume of mercury in the tube is a lot less than the amount of the bulb. Mercury’s volume changes slightly with temperature.

The change in volume drives a long way up the tubing to the mercury column – the column is narrow. The space above the mercury might be full of nitrogen or it may be a vacuum. It has to be less than atmospheric pressure.

Mercury thermometer for sale

So as to calibrate the thermometer, the bulb is made to reach equilibrium with a temperature standard such as an ice/water mixture, and then with another standard like water/vapor, and the tube is divided into intervals between the points. In principle, thermometers made from different material (e.g., colored alcohol thermometers) might be expected to provide different intermediate readings because of various expansion properties. In the training, the substances used are chosen to have reasonably linear expansion characteristics as a function of true thermodynamic temperature, and so they actually give similar results.

Mercury thermometer Amazon

The thermometer was used by the originators of the Celsius and Fahrenheit scales.

Anders Celsius, a Swedish scientist, invented the Celsius scale, which was described as the origin of the Celsius temperature scale in 1742. Celsius used two fixed points on his scale – the temperature of melting ice and the temperature of boiling water. This was actually not a brand new idea since Isaac Newton already worked on something similar. Celsius’ distinction was going to use the condition of melting and not that of freezing. For reaching a calibration of the thermometer, the experiments lasted for 2 winters.

oral mercury thermometer

By doing the same experiment over and over again, he discovered that ice melted on the thermometer at precisely the calibration mark. He found a similar fixed point in the calibration of boiling water to water vapor (if this is done to high accuracy, a variation will be seen with atmospheric pressure – Anders Celsius knew that). At the exact moment that he removed the thermometer from the vapor, the mercury level climbed. This was associated with the rapid heat (and contraction) of the glass!

broken mercury thermometer

1 year later, Frenchman Jean-Pierre Christin proposed to invert the scale with the freezing point at 0 °C (32 °F) and the boiling point at 100 °C (212 °F) while Celsius proposed a method of calibrating a thermometer:

Place the thermometer’s cylinder in melting ice made from pure water and mark the point where the fluid in the thermometer stabilizes fully. This stage is the freeze/thaw point of water.
In precisely the exact same manner, mark the point at which the fluid stabilizes when the thermometer is placed in boiling water vapor.

Divide the length between the two marks to 100 equal parts. Equally, vary with pressure although these points are acceptable for calibration.  Before the discovery of the actual thermodynamic temperature, the thermometer defined the fever. Thermometers made out of unique materials would define different temperature scales (a colored alcohol thermometer would give a slightly different reading than a mercury thermometer at, say half of a scale). In practice, several materials gave temperatures that were similar to each other and, when found, to the thermodynamic temperature.

who invented the mercury thermometer

A special kind of mercury-in-glass thermometer works by having a constriction in the neck close to the bulb. The mercury is pushed up through the constriction by the force of growth, as the temperature slowly rises. The column of mercury breaks at the constriction and can not return to the bulb, thus it remains stationary in the tube when the temperature falls. The observer can read the max temperature. This layout is used in the standard type of thermometer.

non mercury thermometer

A maximum-minimum thermometer is a thermometer which registers the minimum and maximum temperatures attained over a period of time, typically 24 hours. The original design comprises mercury, but solely as a way to indicate the temperature which is indicated by the position of a column of alcohol whose growth is not a thermometer run by the expansion of mercury – mercury-free versions are now also available for purchase.

More information about mercury thermometers is located on Wiki page or check out our outdoor thermometer. If you are a passionate cook we also have oven thermometers!

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Mercury Thermometer