See also:lower than the normal; objectively a quality or
See also:condition of material bodies which gives rise to that sensation . Whether
See also:cold, in the
See also:objective sense, was to be regarded as a
See also:positive quality or merely as
See also:absence of
See also:heat was long a debated question . Thus Robert Boyle, who does not commit himself definitely to either view, says, in his New Experiments and Observations touching Cold, that " the dispute which is the primum frigidum is very well known among naturalists, some contending for the
See also:earth, others for
See also:water, others for the air, and some of the moderns for
See also:nitre, but all seeming to agree that there is some
See also:body or other that is of its own nature supremely cold and by participation of which all other bodies obtain that quality." But with the general acceptance of the dynamical theory of heat, cold naturally came to be regarded as a negative condition, depending on decrease in the amount of the molecular vibration that constitutes heat . The question whether there is a limit to the degree of cold possible, and, if so, where the zero must be placed, was first attacked by the French physicist, G .
See also:Amontons, in 1702–1703, in connexion with his improvements in the air-thermometer . In his instrument temperatures were indicated by the height at which a
See also:column of mercury was sustained by a certain mass of air, the
See also:volume or "
See also:spring " of which of course varied with the heat to which it was exposed . Amontons therefore argued that the zero of his thermometer would be that temperature at which the spring of the air in it was reduced to nothing . On the scale he used the boiling-point of water was marked at 73 and the melting-point of ice at 512, so that the zero of his scale was
See also:equivalent to about -240° on the centigrade scale . This remark-ably close approximation to the
See also:modern value of -273° for the zero of the air-thermometer was further improved on by J . H .
See also:Lambert (Pyrometrie, 1779), who gave the value -270° and observed that this temperature might be regarded as absolute cold . Values of this
See also:order for the absolute zero were not, however, universally accepted about this
See also:period .
Laplace and Lavoisier, for instance, in their
See also:treatise on heat (178o), arrived at values ranging from 1500° to 3000° below the freezing-point of water, and thought that in any case it must be at least 600° below, while
See also:John Dalton in his Chemical Philosophy gave ten calculations of this value, and finally adopted -3000° C. as the natural zero of temperature . After J . P .
See also:Joule had determined the
See also:mechanical equivalent of heat,
See also:Lord Kelvin approached the question from an entirely different point of view, and in 1848 devised a scale of absolute temperature which was inde-pendent of the properties of any particular substance and was based solely on the fundamental
See also:laws of thermodynamics (see HEAT and THERMODYNAMICS) . It followed from the principles on which this scale was constructed that its zero was placed at -273°, at almost precisely the same point as the zero of the air-thermometer . In nature the realms of space, on the probable
See also:assumption that the interstellar
See also:medium is perfectly transparent and diathermanous, must, as was pointed out by W . J . Macquorn Rankine, be incapable of acquiring any temperature, and must therefore be at the absolute zero . That, however, is not to say that if a suitable thermometer could be projected into space it would give a
See also:reading of – 273° . On the contrary, not being a trans-
See also:parent and diathermanous body, it would absorb
See also:radiation from the
See also:sun and other stars, and would thus become warmed .
See also:Professor J . H .
Poynting (" Radiation in theSolar
See also:System," Phil . Trans., A, 1903, 202, p . 525) showed that as regards bodies in the solar system the effects of radiation from the stars are negligible, and calculated that by solar radiation alone a small absorbing sphere at the distance of Mercury from the sun would have its temperature raised to 483° Abs . (21o° C.), at the distance of
See also:Venus to 358° Abs . (85° C.), of the earth to 300° Abs . (27° C.), of
See also:Mars to 243° Abs . (– 3o° C.), and of Neptune to only 54° Abs . (– 219°C.) . The French physicists of the early
See also:part of the 19th century held a different view, and rejected the hypothesis of the absolute cold of space .
See also:Fourier, for instance, postulated a fundamental temperature of space as necessary for the explanation of the heat-effects observed on the
See also:surface of the earth, and estimated that in the interplanetary regions it was little less than that of the terrestrial poles and below the freezing-point of mercury, though it was different in other parts of space (
See also:Ann. chim. phys., 1824, 27, pp . 141, 150) . C .
S . M . Pouillet, again, calculated the temperature of interplanetary space as – 142° C . (Comptes rendus, 1838, 7, p . 61), and
See also:Sir John
See also:Herschel as -150° (Ency . Brit., 8th ed.,
See also:art . " Meteorology," p . 643) . To attain the absolute zero in the laboratory, that is, to deprive a substance entirely of its heat, is a thermodynamical impossibility, and the most that the physicist can hope for is an indefinitely close approach to that point . The lowest steady temperature obtainable by the exhaustion of liquid hydrogen is about – 262° C . (I I° Abs.), and the liquefaction of
See also:helium by Professor Kamerlingh Onnes in 1908 yielded a liquid having a boiling-point of about 4.3° Abs., which on exhaustion must bring us to within about 22 degrees of the absolute zero . (See LIQUID GASES.) For a "cold," in the medical sense, see CATARRH and
See also:RESPIRATORY SYSTEM: Pathology .
COLCOTHAR (adapted in Romanic languages from Arabic...
OLD COLD HARBOR
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