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Further experiments with liquid helium. C. On the change of electric resistance of pure metals at very low temperature etc. IV. The resistance of pure mercury at helium temperatures.
Eduard Ijdo, Leiden 1911 - First printing of the first announcement of the discovery of superconductivity, the disappearance of electrical resistance in certain materials at very low temperatures. "Of all the discoveries in condensed matter physics during the 20th century, some might call superconductivity the "crown jewel". Others might say that honour more properly belongs to semiconductors or the elucidation of the structure of DNA, given the benefits that both have brought to humanity. Yet no-one would deny that when a team led by Heike Kammerlingh Onnes stumbled across superconductivity. the scientific community was caught by complete surprise" (P. M. Grant, "Down the path of least resistance", Physics World 24, April 2011, p, 18). In the course of the same experiment, Kammerlingh Onnes and his team also made the first observation of superfluidity (see below). Very rare in original printed wrappers."Kammerlingh Onnes’s first experiment with liquid helium was carried out on 8 April 1911 [reported in the offered paper]. "The experiment was started at 7am, and Kamerlingh Onnes arrived when helium circulation began at 11:20am. The resistance of the mercury fell with the falling temperature. After a half hour, the gold resistor was at 140 K, and soon after noon the gas thermometer denoted 5 K. The valve worked "very sensitively." Half an hour later, enough liquid helium had been transferred to test the functioning of the stirrer and to measure the very small evaporation heat of helium. "The team established that the liquid helium did not conduct electricity, and they measured its dielectric constant. Holst made precise measurements of the resistances of mercury and gold at 4.3 K. Then the team started to reduce the vapor pressure of the helium, and it began to evaporate rapidly. They measured its specific heat and stopped at a vapor pressure of 197 mmHg (0.26 atmospheres), corresponding to about 3 K. "Exactly at 4pm, says the notebook, the resistances of the gold and mercury were determined again. The latter was, in the historic entry, "practically zero." The notebook further records that the helium level stood quite still. "The experiment continued into the late afternoon. At the end of the day, Kamerlingh Onnes finished with an intriguing notebook entry: "Dorsman [who had controlled and measured the temperatures] really had to hurry to make the observations." The temperature had been surprisingly hard to control. "Just before the lowest temperature [about 1.8 K] was reached, the boiling suddenly stopped and was replaced by evaporation in which the liquid visibly shrank. So, a remarkably strong evaporation at the surface." Without realizing it, the Leiden team had also observed the superfluid transition of liquid helium at 2.2 K. Two different quantum transitions had been seen for the first time, in one lab on one and the same day! "Three weeks later, Kamerlingh Onnes reported his results at the April meeting of the [Koninklijke Nederlandse Akademie van Wetenschappen]. For the resistance of ultrapure mercury, he told the audience, his model had yielded three predictions: (1) at 4.3 K the resistance should be much smaller than at 14 K, but still measurable with his equipment; (2) it should not yet be independent of temperature; and (3) at very low temperatures it should become zero within the limits of experimental accuracy. Those predictions, Kamerlingh Onnes concluded, had been completely confirmed by the experiment" (van Delft & Kes, p. 41). "Kamerlingh Onnes’s career at Leiden spanned four decades. His central work was the measurement of properties of matter at very low temperatures. Researchers in other countries had recently succeeded in liquefying air (78.6 K), and Kamerlingh Onnes set out to follow them. It was not until 1892 that his apparatus for liquefying air and oxygen was in operation .With this apparatus, which produced large quantities of liquid air and oxygen, Kamerlingh Onnes pursued research lines following Van der Waals (molecular pr [Attributes: First Edition]
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