The Fahrenheit temperature scale is based on 32° for the freezing point of water and 212° for the boiling point of water, with the interval between the two being divided into 180 equal parts. The scale was proposed in 1724 by the physicist Daniel Gabriel Fahrenheit, who originally took as the zero of his scale the temperature of an equal ice-salt mixture and selected the values of 30° and 90° for the freezing point of water and normal body temperature, respectively. These later were revised to 32° and 96°, but the final scale required an adjustment to 98.6° for the latter value. Fahrenheit chose these values based on three fixed temperature points: the freezing point of water, human body temperature, and the coldest point that he could repeatably cool a solution of water, ice, and a kind of salt, ammonium chloride. He chose these points based on an older temperature scale created by Ole Christensen Rømer 20 years earlier, which had brine (the salt-/ice- water mixture) freezing at 0°, water at 7.5°, normal human body temperature at 22.5°, and water’s boiling point at 60°. Fahrenheit decided to multiply each value by a factor of about 4 to make calculations easier and to increase the precision of the scale by increasing the number of distinguishable parts within it.