None of that seems systematic to me. Very arbitrary... This human doesn't normally make his ice cubes from ammonium brine.That's because Fahrenheit designed the scale using reference points based on (gasp! shock!) ordinary human experience.
He set the zero point at the freezing temperature of a brine solution. Salts lower the freezing point of solutions...the particular ammonium salt he used freezes at temperatures 32° below the point where plain water freezes.
He also set 100° to be the temperature registered on the thermometer when held in the mouth...normal human body temperature.
As later measurements became more precise, the scale was altered to set the boiling point of plain water exactly 180° above its freezing point, which resulted in normal body temperature being shifted down slightly to 98.6°.
I think using normal human experience, I would set zero at the freezing point of water and 100 at the point where a Hershey Bar turns to mush.