Water triple point temperature: 272.16K or 273.1598K?

[Diego Saravia]

Water triple point T is 272.16K

http://www.omega.com/temperature/z/pdf/z186-193.pdf
http://media4.physics.indiana.edu/~courses/p340/S11/Lecture_Presentations/ITS-90_metrologia.pdf


But several internet pages say that water triple point is at 273.1598 K
http://www.quimica.es/enciclopedia/Punto_triple.html
http://temperaturemeasurement.wordpress.com/2010/07/08/international-temperature-scale/http://www.duncaninstr.com/pdfs/Temperature%20Measurement.pdf
http://es.scribd.com/doc/61755350/Punto-Triple-y-Punto-Critico

Which is the source of this number 273.1598?

 

[Borek]

Perhaps a historical artifact? Original definition of deg C used melting and boiling temperatures of water, perhaps 273.1598 is a triple point measured using these old degrees. In 1954, after Kelvin was defined as exactly $\frac 1 {273.16}$ both Celsius and Kelvin slightly changed. But I am just guessing.

 

[ErolDynamics]

they are so closed numbers not to to much go through that :D

 

[256bits]

The first site you reference states

La única combinación de presión y temperatura a la que el agua, hielo y vapor de agua pueden coexistir en un equilibrio estable se produce exactamente a una temperatura de 273.1598 K (0.0098 ° C) y a una presión parcial de vapor de agua de 611,73 pascales (6,1173 milibares, 0,0060373057 atm).

which I take that the one temperature is exact.

I think Borus is correct. The defining of the Kelvin scale left the celsius scale to be redefined as the triple and boiling point of water and that was "assumed" to be 273.16 K. Experimentation afterwards found the actual triple point was not 0.01 C and therin lies the descrepancy.

 

[nasu]

Water triple point T is 272.16K

http://www.omega.com/temperature/z/pdf/z186-193.pdf
http://media4.physics.indiana.edu/~courses/p340/S11/Lecture_Presentations/ITS-90_metrologia.pdf


But several internet pages say that water triple point is at 273.1598 K
http://www.quimica.es/enciclopedia/Punto_triple.html
http://temperaturemeasurement.wordpress.com/2010/07/08/international-temperature-scale/http://www.duncaninstr.com/pdfs/Temperature%20Measurement.pdf
http://es.scribd.com/doc/61755350/Punto-Triple-y-Punto-Critico

Which is the source of this number 273.1598?

It seems that the question is "what is the source of the 272.16 value" that you show here.
I looked at the first link indicated in the post. I did not read it all, it's a long pdf. However it refers several times to the triple point temperature as 273.15..
The second link does not work for me.

It is somehow interesting that the triple point of the ionic liquid 1-Methylimidazole is reported as 272.16. Is it possible that you confused some values?
The link is here:
http://www.chemie1.uni-rostock.de/pci/emelyanenko/publications/62.pdf

For water it is about 273.16K
http://physics.nist.gov/cuu/Units/kelvin.html