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Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity . At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temperature of −269 °C (−452.20 °F; 4.15 K).
A melting-point apparatus is a scientific instrument used to determine the melting point of a substance. Some types of melting-point apparatuses include the Thiele tube , Fisher-Johns apparatus, Gallenkamp (Electronic) melting-point apparatus and automatic melting-point apparatus.
2 He helium; use: 4.222 K: −268.928 °C: ... "Corrected Values for Boiling Points and Enthalpies of Vaporization of Elements in ... Melting points of the elements ...
The Thiele tube, named after the German chemist Johannes Thiele, is a laboratory glassware designed to contain and heat an oil bath. Such a setup is commonly used in the determination of the melting point or boiling point of a substance. The apparatus resembles a glass test tube with an attached handle.
Boca Raton, Florida, 2003; Section 6, Fluid Properties; Critical Constants. Also agrees with Celsius values from Section 4: Properties of the Elements and Inorganic Compounds, Melting, Boiling, Triple, and Critical Point Temperatures of the Elements Estimated accuracy for Tc and Pc is indicated by the number of digits.
The temperature at standard pressure should be equal to the normal boiling point, but due to the considerable spread does not necessarily have to match values reported elsewhere. log refers to log base 10 (T/K) refers to temperature in Kelvin (K) (P/Pa) refers to pressure in Pascal (Pa)
2 He helium; use: 0.0829 CRC: 0.08 LNG: 0.0829 WEL: 0.083 ... Values refer to the enthalpy change in the conversion of liquid to gas at the boiling point (normal, 101 ...
2 He helium-4; Hoffer et al. 0.19085 ... (He-I at boiling point: 4.222 K) ... The suggested values for liquid densities refer to "at the melting point (m.p.)" by default.