Meet Daniel Fahrenheit. He was a German physicist and a glassblower. He loved making thermometers in the early 1700s.
He wanted a scale that was practical for everyday life. He didn’t care about the freezing point of water the way we do. He cared about brine.
Yes, brine. That salty, icy slush you see on roads in winter. He used a mixture of water, ice, and ammonium chloride (a type of salt) to get his zero point.
A Very Salty Zero
So, 0°F is not the freezing point of pure water. It’s the freezing point of a specific saltwater mixture. Imagine designing a scale based on your driveway in January.
Fahrenheit then used the human body’s temperature as his upper benchmark. He set that at 96°F. (Spoiler: He was off by about two degrees, but close enough for the 1700s.)
This left the freezing point of pure water smack-dab in the middle. It landed at 32°F purely by arithmetic. It was a side effect, not the goal.
