The boiling point of water

[AngloScot]

It seems funny to me how the boiling point of water is exactly 100 degrees celcius. Is it just a coincidence that it is such a nice round number or was the celcius measurement built around this? Thanks.

[greenday]

Not coinidence at all. The scale was created so water freezes at 0 and boils at 100.

[Clanad]

And in non-metric countries the same water freezes at 32 degrees Fahrenheit and boils at 212 degrees F at sea level on a standard day... go figure...

The Swedish scientist Anders Celsius (1701-1744), who invented the Celsius temperature scale in 1742, actually set the scale with 0 as the boiling point of water and 100 as the freezing point. The scale was reversed soon after its invention.
The Fahrenheit temperature scale was devised in 1714 by the German scientist G.D. Fahrenheit. His scale has 180 degrees between the freezing point of water which he set at 32 degrees, and the boiling point of water which he set at 212 degrees. The Fahrenheit scale is still in general use but is not commonly in scientific use where Celsius and Kelvin are the preferred scales.The Kelvin temperature scale was devised in 1848 by William Thomson, Lord Kelvin. His scale was not based on any specific substance. Instead, the size of the units (degrees) was set at exactly the same as those of the Celsius scale. However, 0 (zero) on the Kelvin scale is absolute zero, a theoretical temperature at which all substances have no heat energy...

[landie]

The Celcius (Centigrade) scale was created to achieve exactly this result. If you had an unmarked tube of mercury ( or, I think, any other liquid) you could create your own thermometer as follows.

Insert your liquid filled tube in crushed ice and let the temperature equalise. Put a mark on the tube at the level of the liquid, 0 deg C. Do the same in water wich is boiling, at normal sea level pressure, and make a similar mark. This is 100 deg C.

The distance between the two marks can then be divided equally into 100 divisions and you have your thermometer

[archbishop]

And normal sea level in The UK is measured at Newlyn in Cornwall.

[LordyGeordie]

incidentally the fahrenheit scale was set so that 0 degrees F was the temperature at which salty water froze and 100 degrees F was the temperature of the human body (37 degrees c).

However, he was a bit out on both temperatures

[Thunderchild]

well for salty water u would have to see about the % of salt