華氏溫標參考甚麼物質而制訂？

http://zh.wikipedia.org/wiki/%E5%8D%8E%E6%B0%8F%E6%B8%A9%E6%A0%87

你先咬文嚼字就知點解

他使用三個參考溫度來標示他的刻度。將溫度計放入由冰、水以及氯化銨所混合而成的鹽水中，量得的刻度即為零度。鹽水是一種製冷混合物，可以將溫度自動維持在華氏零度。第二個刻度是32度，為將溫度計放恰好有冰形成於表面的水中所量得的刻度。[2]第三個刻度為96度，為將溫度計含入口中，或夾在腋下時所量得的刻度。

係當時好明顯已經有溫度計，溫度計有刻度，但冇數字，以上好清楚表明華氏如何制定數字，而非刻度。

The Fahrenheit scale was first designed to be used in daily life, not for scientific use. The scale was based on an old scale, the Romer scale, used by the Danish astronomer, Ole Romer. Because Romer hated to use negative numbers, thus the zero degrees was fixed to be the lowest temperature that could be achieved in Denmark, the country where Romer lived.

Fahrenheit then used the Romer scale as a basis and his body temperature as the upper fixed point, which he determined to be 90 degrees at first. Later, after some adjustment and refinement, the human body temperature was fixed at 98.6 degrees.

The use of the temperature of a mixture of water, ice and ammonium chloride as "zero degree" on the scale was only used as an explanation, but not the origin, when Fahrenheit presented his scale at the Royal Society in London.

The following web-page gives a good description on the history of how the Fahrenheit scale originates.

ttp://www.straightdope.com/columns/read/845/on-the-fahrenheit-scale-why-is-32-freezing-and-212-boiling

wiki其實有
佢講到話用brine(鹽水)同NH4Cl