Leiden scale

 ( Obsolete Units Of Measurement ) 

The Leiden scale ( °L or ÐL) is a temperature scale that was used to calibrate low-temperature indirect measurements in the early 20th century, by providing conventional values (in , then termed "degrees Kelvin") of helium vapour pressure. The scale dates back at around 1894, when Heike Kamerlingh Onnes established his cryogenics laboratory in Leiden, Netherlands. It was used below −183 °C, the starting point of the International Temperature Scale in the 1930s (Awbery 1934). The boiling points of standard hydrogen (−253 °C), consisting of 75% orthohydrogen and 25% parahydrogen, and oxygen (−183 °C) were used as fixed points, corresponding to zero and 70 on the scale respectively.

• Outline of metrology and measurement

• Berman, A.; Zemansky, M. W.; and Boorse, H. A.; Normal and Superconducting Heat Capacities of Lanthanum, Physical Review, Vol. 109, No. 1 (January 1958), pp. 70–76. Quote:

"The 1955 Leiden scale¹³ was used to convert helium vapor pressures into temperatures ... (13) H. van Dijk and M. Durieux, in Progress in Low Temperature Physics II, edited by C. J. Gorter (North-Holland Publishing Company, Amsterdam, 1957), p. 461. In the region of calibration the 1955 Leiden scale, T_L55, differs from the Clement scale, T_55E, by less than 0.004 deg." (emphasis added)

• Grebenkemper, C. J.; and Hagen, John P.; The Dielectric Constant of Liquid Helium, Physical Review, Vol. 80, No. 1 (October 1950), pp. 89–89. Quote:

"The temperature scale used was the 1937 Leiden scale." (emphasis added)

• Awbery, J. H.; Heat, Rep. Prog. Phys. 1934, No. 1, pp. 161–197 . Quote:

"It should be mentioned that below −183 °C, the Leiden workers do not entirely agree with some of the other cryogenic laboratories, but use a scale of their own, generally known as the Leiden scale." (emphasis added)

• H. van Dijk, M. Durieux.; The Temperature Scale in the Liquid Helium Region, Progress in Low Temperature Physics. - 1957. - Vol. 2. — P. 431–464.
• Hubbard, Joanna; Are icebergs made of salt water or fresh water? Archived at the Wayback Machine (07-16-2011)