ON THE SPECIFIC HEATS OF TUNGSTEN, MOLYBDENUM, AND COPPER

1933 ◽  
Vol 8 (3) ◽  
pp. 282-303 ◽  
Author(s):  
H. L. Bronson ◽  
H. M. Chisholm ◽  
S. M. Dockerty
Keyword(s):  
Specific Heat ◽  
Linear Equations ◽  
Adiabatic Calorimeter ◽  
Absolute Temperature ◽  
Large Temperature ◽  
Average Deviation ◽  
Specific Heats ◽  
New Type ◽  
The Individual ◽  
Theoretical Considerations

This paper contains the results of a long series of determinations of the specific heats of tungsten, molybdenum, and copper from − 20° to 500 °C.A new type of all-copper adiabatic calorimeter has been designed and used. The complete elimination of water from the calorimeter removed several sources of error and resulted in increased reliability and accuracy.Two entirely different methods were used in determining the specific heats. The usual "method of mixtures" was used to determine the mean specific heat for a large temperature change and was applied to all three metals over the entire range of temperature. The specific heat of copper was also determined for 5- or 10-degree intervals from − 5° to 110 °C. by heating the calorimeter electrically.It has been quite definitely shown that the specific heats of these metals over a temperature range as large as 0° to 500 °C. cannot be expressed as a linear function of the temperature. An equation of the form Cp = A + BT − C/T2 was arrived at from theoretical considerations and the constants determined empirically with the following results:—[Formula: see text]where the unit of heat is the 20-degree calorie and T is absolute temperature. The average deviation of the individual determinations from the values calculated by these equations was only about 0.1%.As a matter of convenience and for purposes of comparison, linear equations applicable over smaller ranges of temperature have also been given.

The specific heats of three paramagnetic salts at very low temperatures

1956 ◽  
Vol 237 (1210) ◽  
pp. 395-403 ◽  
Keyword(s):  
Specific Heat ◽  
Absolute Temperature ◽  
Magnesium Nitrate ◽  
Paramagnetic Resonance ◽  
Specific Heats ◽  
Ammonium Alum ◽  
Relaxation Measurements ◽  
Ferric Ammonium ◽  
The Absolute ◽  
Measured Specific Heat

The specific heats of three paramagnetic salts, neodymium magnesium nitrate, manganous ammonium sulphate and ferric ammonium alum, have been measured at temperatures below 1°K using the method of γ -ray heating. The temperature measurements were made in the first instance in terms of the magnetic susceptibilities of the salts, the relation of the susceptibility to the absolute temperature having been determined for each salt in earlier experiments. The γ -ray heatings gave the specific heat in arbitrary units. The absolute values of the specific heats were found by extrapolating the results of paramagnetic relaxation measurements at higher temperatures. The measured specific heat of neodymium magnesium nitrate is compared with the value calculated from paramagnetic resonance data, and good agreement is found.

scholarly journals III. Investigations of the specific heat of solid bodies

1865 ◽  
Vol 155 ◽  
pp. 71-202 ◽  
Keyword(s):  
Specific Heat ◽  
Thermal Action ◽  
General View ◽  
Specific Heats ◽  
General Law ◽  
Different Temperatures ◽  
The Times ◽  
The Individual ◽  
Solid Bodies

I. About the year 1780 it was distinctly proved that the same weights of different bodies require unequal quantities of heat to raise them through the same temperature, or on cooling through the same number of thermometric degrees, give out unequal quantities of heat. It was recognized that for different bodies the unequal quantities of heat, by which the same weights of different bodies are heated through the same range, must be determined as special constants, and considered as characteristic of the individual bodies. This newly discovered property of bodies Wilke designated as their specific heat , while Crawford described it as the comparative heat, or as the capacity of bodies for heat . I will not enter upon the earliest investigations of Black, Irvine, Crawford, and Wilke, with reference to which it may merely be mentioned that they depend essentially on the thermal action produced when bodies of different temperatures are mixed, and that Irvine appears to have been the first to state definitely and correctly in what manner this thermal action (that is, the temperature resulting from the mixture) depends on the original temperature, the weights, and the specific heats of the bodies used for the mixture. Lavoisier and Laplace soon introduced the use of the ice-calorimeter as a method for determining the specific heat of bodies; and J. T. Mayer showed subsequently that this determination can be based on the observation of the times in which different bodies placed under comparable conditions cool to the same extent by radiation. The knowledge of the specific heats of solid and liquid bodies gained during the last century, and in the first sixteen years of the present one, by these various methods, may be left unmentioned. The individual determinations then made were not so accurate that they could be compared with the present ones, nor was any general conclusion drawn in reference to the specific heats of the various bodies. 2. Dulong and Petit’s investigations, the publication of which commenced in 1818, brought into the field more accurate determinations, and a general law. The investigations of the relations between the specific heats of the elements and their atomic weights date from this time, and were afterwards followed by similar investigations into the relations of the specific heats of compound bodies to their composition. In order to give a general view of the results of these investigations, it is desirable to present, for the elements mentioned in the sequel, a synopsis of the atomic weights assumed at different times, and of certain numbers which stand in the closest connexion with these atomic weights.

The nuclear specific heat in paramagnetic cupric salts at temperatures below 1° K I. Thermodynamic measurements made from a study of the field-dependence of the adiabatic susceptibility

1950 ◽  
Vol 203 (1074) ◽  
pp. 375-391 ◽  
Keyword(s):  
Magnetic Susceptibility ◽  
Specific Heat ◽  
Field Dependence ◽  
Absolute Temperature ◽  
Potassium Sulphate ◽  
Specific Heats ◽  
Magnetic Cooling ◽  
Thermodynamic Measurements ◽  
Small Fields ◽  
The Absolute

Thermodynamic measurements have been made at temperatures below 1°K, obtained by the method of magnetic cooling, on copper potassium sulphate and on a diluted copper Tutton salt. A study has been made of the field- dependence (for small fields) of the adiabatic susceptibility of the cooled and thermally isolated salt, the measurements covering the range of temperature from 1°K down to 0.05°K for copper potassium sulphate, and to 0.025° K for the dilute salt. From these measurements the entropy and magnetic susceptibility are determined as functions of the absolute temperature. It is concluded that for both salts the susceptibility follows a Curie-Weiss law, the values of ∆ being 0.034 and 0.0048º K respectively; the specific heats are of the form ∆ / T 2 , the values found for A being 6.1x10 -4 R for copper potassium sulphate and 1.98x10 -4 R for the dilute salt.Deviations from this behaviour in a ferromagnetic direction are found for copper potassium sulphate below 0.07° K.

Thermal Properties of Alcaline-Earth-Oxides I. Specific heat measurements 1-3 Centre National de Recherches sur les Tres Basses Temperatures

1969 ◽  
Vol 24 (11) ◽  
pp. 1794-1800 ◽  
Author(s):  
E. Gmelin
Keyword(s):  
Thermal Properties ◽  
Specific Heat ◽  
Adiabatic Calorimeter ◽  
Heat Capacities ◽  
Temperature Calibration ◽  
Specific Heats ◽  
Thermal Switch ◽  
Heat Capacities Of Solids ◽  
Better Than

Abstract The heat capacities of MgO, CaO, SrO, BaO, having NaCl-structure, have been measured with an adiabatic calorimeter capable to measure heat capacities of solids between 1.2 and 340 °K. A mechanical thermal switch is used for specimen cooling and the temperature calibration above 4 °K is performed with a gas thermometer. The values of the specific heats, Cv , are tabulated. The entropies at 273.15 °K are 27.19; 38.3; 51.9; and 66.9 for MgO. CaO, SrO and BaO respectively, in J/mol °K. The accuracy of the measurements is estimated to be better than 0.8% (smoothed curve).

scholarly journals The thermal capacity of pure iron

1940 ◽  
Vol 174 (956) ◽  
pp. 1-15 ◽  
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Thermal Capacity ◽  
Total Heat ◽  
Large Temperature ◽  
Specific Heats ◽  
The Past ◽  
Heat Curve ◽  
Different Temperatures ◽  
The Subject

Although the heat capacity of iron at different temperatures has been the subject of a number of investigations in the past, it is only recently that iron of purity greater than 99.9 % has been available. Furthermore, in most previous determinations the property actually measured has been the total heat over a relatively large temperature range. Specific heats deduced from such measurements are liable to appreciable error, since if the total heat curve is smoothed, small fluctuations in the specific heat will be concealed, whereas if the actual observations are retained without smoothing, fluctuations which have no physical existence may appear in the result. Thus, suppose that the total heat is measured from 50 to 145 and from 50 to 155° C, the former being in error by 1 part in 1000 in excess and the latter the same amount in defect, the error in the specific heat over the range 145-155° C will be almost 2%. Evidently a real variation of 1 or 2% would be liable to pass unnoticed if any smoothing is undertaken, and conversely, fluctuations of this order may be introduced spuriously if the observations are used without smoothing. In general, calorimetry from high temperatures cannot be carried out to an accuracy of 1 part in 1000, and in any case, even this accuracy is insufficient at temperatures of the order of 1000° C.

HIGH TEMPERATURE CALORIMETRY: I. A NEW ADIABATIC CALORIMETER

1950 ◽  
Vol 28a (1) ◽  
pp. 44-50 ◽  
Author(s):  
L. D. Armstrong
Keyword(s):  
High Temperature ◽  
Specific Heat ◽  
Temperature Interval ◽  
High Temperatures ◽  
Adiabatic Calorimeter ◽  
Small Temperature ◽  
Specific Heats ◽  
Definite Temperature

In this paper is described a new calorimeter for the measurement of specific heats at high temperatures, by the adiabatic method. The advantage is that the specific heat at a definite temperature can be determined by a measurement taken over a small temperature interval, with a precision of 1% or better, throughout the range 400 °C. to 800 °C. This permits a study of specific heat anomalies in this range.

Temperature-dependent Specific Heats of Dry Soil Materials

1975 ◽  
Vol 12 (2) ◽  
pp. 209-212 ◽  
Author(s):  
B. D. Kay ◽  
J. B. Goit
Keyword(s):  
Specific Heat ◽  
Functional Relation ◽  
Absolute Temperature ◽  
Temperature Dependent ◽  
Specific Heats ◽  
Proportionality Constant ◽  
Single Temperature ◽  
Different Temperatures ◽  
Dry Soil ◽  
The Absolute

Specific heat measurements have been made on several soil materials at different temperatures in order to obtain a generalized functional relation between specific heat and temperature. Specific heats were found to vary linearly with temperature from 200 to 300 °K (−73 °C to + 27 °C) and extrapolated close to zero at 0 °K. Consequently, the functional relation between specific heat and temperature for soil materials may be approximated as Cp = mT where Cp is the specific heat, T is the absolute temperature (°K), and m is a proportionality constant. Such a relation permits the prediction of the specific heats at any temperature normally encountered in the field once reliable specific heats have been determined at a single temperature.

THE HEAT CONTENT OF WATER ADSORBED ON CELLULOSE

1939 ◽  
Vol 17b (1) ◽  
pp. 40-50 ◽  
Author(s):  
J. H. Shipley ◽  
W. Boyd Campbell ◽  
O. Maass
Keyword(s):  
Heat Capacity ◽  
Experimental Technique ◽  
Heat Content ◽  
Bound Water ◽  
Adsorbed Water ◽  
Adiabatic Calorimeter ◽  
Temperature Range ◽  
Specific Heats ◽  
New Type

The heat capacity of water adsorbed on cellulose has been measured by means of a new type of adiabatic calorimeter and a new experimental technique. Measurements have been made with 2, 4, 8, and 12% adsorbed water over the temperature range − 35° to + 25 °C. with considerable accuracy. A mechanism, that of a change in the amount of bound water with the temperature, has been suggested to explain the high values obtained for the apparent specific heats of adsorbed water.

New Type of Two Degree of Freedom Motor Three-Dimensional Tooth Layer Field Application and Solution

2013 ◽  
Vol 391 ◽  
pp. 232-236
Author(s):  
Wen Huan Yang ◽  
Hai Xu Chen ◽  
Shuang Xie ◽  
Chun Ren Fang
Keyword(s):  
Linear Equations ◽  
Three Dimensional ◽  
Field Application ◽  
Degree Of Freedom ◽  
Refined Method ◽  
New Type ◽  
Type Motor ◽  
Quasi Newton ◽  
Two Degree Of Freedom ◽  
Non Linear Equations

A new Multi-degree of freedom motor and its establishing of teeth layer parameters have been introduced in the paper, also including application method of database, namely using Quasi-Newton methods to solve the non-linear equations of the new motors magnetic circuit net, formed a refined method for designing and analyzing of motor. The establishment of 3d tooth layer parameters database, is provided for the calculation in the design of the new type motor conveniently.

Specific heats of polymer powders by differential scanning calorimetry

1982 ◽  
Vol 60 (14) ◽  
pp. 1853-1856 ◽  
Author(s):  
Eva I. Vargha-Butler ◽  
A. Wilhelm Neumann ◽  
Hassan A. Hamza
Keyword(s):  
Differential Scanning Calorimetry ◽  
Specific Heat ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Specific Heats ◽  
Powdered Form ◽  
Polymer Powders

The specific heats of five polymers were determined by differential scanning calorimetry (DSC) in the temperature range of 300 to 360 K. The measurements were performed with polymers in the form of films, powders, and granules to clarify whether or not DSC specific heat values are dependent on the diminution of the sample. It was found that the specific heats for the bulk and powdered form of the polymer samples are indistinguishable within the error limits, justifying the determination of specific heats of powders by means of DSC.

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