Daniel Gabriel Fahrenheit, designed the famous temperature scale and the mercury thermometer


May 24, 1686, Danzig (now Gdansk in what is now Poland) – September 16, 1736, in The Hague, Netherlands

After the death of his parents after eating poisonous mushrooms, at the age of 15, he made study trips to Germany, England and Denmark where in 1708 he met Ole Rømer (the first person to determine the speed of light). He later settled in Amsterdam, at that time one of the main manufacturing centers for scientific instruments, where he worked as a glass blower and began to develop precision instruments creating the water (1709) and mercury (1714) thermometers.

At that time, thermometers used alcohol as a reference liquid and based on the knowledge that Fahrenheit had acquired from Rømer about the thermal expansion of metals, he was able to replace it with mercury and discovered a method to purify it so that it did not adhere to the walls. of the tube.

Termómetro de mercurio

In 1717, he published "Acta Editorum" in which he proposed a new thermometric scale that bore his name. It was designed using as a reference a mixture of water and ammonium chloride salt in equal parts, in which the freezing and boiling temperatures are lower than that of water.

The freezing value of that mixture he called 0°F (degrees Fahrenheit), his body temperature 96°F, and the freezing temperature of water without salts, 32°F. In particular, 212°F corresponds to 100°C, so the relationship between them is:

Ecuación Fahrenheit-Celsius

The reason for assigning the body temperature the value of 96 was so that between zero and that value there would be a scale formed by a dozen divisions, each of them subdivided into eight parts, that is, 12 x 8 = 96.

Consequently, by covering a wider interval, the Fahrenheit scale allows greater precision than the centigrade (later designed by Anders Celsius) when defining a specific temperature.

This scale is the most widely used in the United States and until very recently in the United Kingdom (which currently uses the metric system).

In 1724, Fahrenheit published "Philosophical Transactions" that dealt with several topics, among others, about the boiling temperatures of various liquids, the solidification of water in a vacuum, and the possibility of obtaining liquid water at a temperature lower than that of its point of regular freezing. That same year he became a member of the Royal Society, the oldest scientific society in the United Kingdom and one of the oldest in Europe.

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