Absolute Thermal Conductivity Research Articles

The thermal conductivities of oxygen and nitrogen

The interest in the determination of the thermal conductivities of oxygen and nitrogen lies partly in their relation to the thermal conductivity of air. The latter is the medium which practically every experimenter on gaseous thermal conduction has investigated, and has therefore become the standard substance in this field of research. Being a mixture chiefly of the gases oxygen and nitrogen, with the latter in the greater proportion, the value of its conductivity should lie between those of oxygen and nitrogen and should be nearer that of nitrogen than that of oxygen. The authors, in common with Weber and Todd, have verified this experimentally, the only observer finding these con­ductivities in a contrary order being Winkelman, who used a cooling thermometer method. The following is a table of the results hitherto obtained for the absolute thermal conductivities at 0° C. of oxygen and nitrogen, together with their authors’ results for air. The values marked with an asterisk have been deduced by applying the temperature coefficient, 0.0029 per 0° C., to results which were obtained at temperatures above 0° C. Weber has recently published a new result for the thermal conductivity of air, 0.0000574, which is about 1 per cent. higher than his old value. Assuming that, if his results for oxygen and nitrogen were revised, they would be increased in the same proportion, his new values for these gases would be—oxygen 0.0000583, and nitrogen 0.0000572.

XII.—The Absolute Thermal Conductivity of Nickel

The experiments described in this paper were commenced with the view, not only of determining the absolute thermal conductivity of nickel, but also of comparing the results found by Forbes's and Ängstrom's methods for the same specimen. Although some readings were taken for Ängstrom's method, that part of the investigation was not completed, because it was found that the experimental errors — unavoidable, on account of the necessity of measuring rapidly changing temperatures—would be too great for the results to be of any value. The thermal conductivity of a portion of the bar of nickel used for Forbes's method was determined by a direct method involving the determination only of steady temperatures, and the results so obtained are given in the latter portion of this paper.

IV. The absolute thermal conductivities of copper and iron

The experiments described in the paper were undertaken with the object of determining the theoretical conductivity at different temperatures of iron, and, in particular, of pure electrolytically deposited copper. The method adopted was that due to Forbes, with two modifications. ( a .) The thermo-electric method of determining temperature was employed.

X. The absolute thermal conductivities of iron and copper

The experiments described in this paper were undertaken at the suggestion of Pro­fessor A. Gray, M. A., University College, Bangor, with the object of contributing something to the results still necessary to establish the experimental work bearing on the absolute thermal conductivity of metals on a more satisfactory basis. They were also intended to furnish a determination of the absolute conductivity of pure copper at different temperatures. The data already accumulated on the thermal conductivities of iron and copper are due chiefly to Ångström, Forbes, Neumann, Tait and Mitchell, and more recently to Kirchhoff and Hansemann and Lorenz.

Scientific Serials

The American Journal of Science, July.—The change of heat conductivity on passing isothermally from solid to liquid, by C. Barus. The method employed was a modification of Weber's, who placed a thin, wide, plane-parallel plate or layer of the substance to be examined between and in close contact with two thick plates of copper. The system was first heated so as to be at a given temperature throughout. It was then suddenly and permanently cooled at the lower surface, and the time-rate at which heat travelled from the top plate to the bottom plate, through the intervening layer, was measured by a thermo-couple. From these data the absolute thermal conductivity of the layer may be computed, the constants of the system being known. In the experiments discussed, the liquid was thymol, which can be kept either solid or liquid between 0° and 50° C. This was heated above its melting point, and introduced through a central hole in the upper plate; it was then allowed to cool down until undercooled. The temperature was regulated by enclosing the whole apparatus in a sheet-iron jacket, through which water was kept circulating. The lower plate could be cooled by flushing it with water from below. The difference of temperature of the plates was measured by means of a copper german-silver couple. The liquid was solidified by introducing a crystal through the central hole. The results obtained gave for the absolute conductivity of thymol in g/cs:

XVI. On a method of measuring the absolute thermal conductivity of crystals and other rare substances.—Part I

XVI. <i>On a method of measuring the absolute thermal conductivity of crystals and other rare substances</i>.—Part I

On a Method of measuring the Absolute Thermal Conductivity of Crystals and other rare Substances - Part I

On a Method of measuring the Absolute Thermal Conductivity of Crystals and other rare Substances - Part I