What is F? How to convert it into degrees Celsius?

F is the symbol of Fahrenheit, which is converted into:

f = c× 1.8+32； C=( F-32)÷ 1.8

The Fahrenheit scale is defined as: at standard atmospheric pressure, the melting point of ice is 32℉, the boiling point of water is 2 12℉, and there are 180 divisions in the middle, and each division is 1 Fahrenheit.

Before 1970, Britain and its former colonial countries mostly used Fahrenheit temperature scale. In the late 20th century, most countries in the world began to switch to the international system of units, and centigrade scale was used to replace the Fahrenheit scale. Up to now, only a few countries and regions such as the United States, Cayman Islands and Belize still keep the Fahrenheit scale as the legal unit of measurement.

According to a diary written by German scientist Warren Heit in 1724, he marked his scale with three reference temperatures. Put the thermometer into the salt water mixed with ice, water and ammonium chloride, and the scale of the quantity is zero, because this is the lowest temperature item that can be made at that time.

Salt water is a refrigeration mixture that can automatically keep the temperature at zero degrees Fahrenheit. The second scale is 32 degrees, which is measured by putting the thermometer into water with frozen surface. The third scale is 96 degrees, which is measured by putting the thermometer in your mouth or under your arm. Warren Hite said that with this scale, mercury boils at about 600 degrees.

References:

Baidu encyclopedia-Fahrenheit