scholarly journals VI.—Bakerian Lecture.—The specific heats of metals, and the relation of specific heat to atomic weight

1900 ◽  
Vol 194 (252-261) ◽  
pp. 233-255 ◽  
Keyword(s):  
Physical Properties ◽  
Specific Heat ◽  
Pure State ◽  
Atomic Weight ◽  
Melting Points ◽  
Specific Heats ◽  
The Subject ◽  
The Difference ◽  
Melting And Solidification ◽  
Cobalt And Nickel

The experiments recorded in the following pages were begun nearly five years ago, at a time when opinion was still much divided as to the atomic weight of cobalt and nickel. It seemed to me that it would be a step in advance if it could be settled which of the two is the greater, for while perhaps the majority of chemists represented the atomic weight of cobalt as greater than that of nickel, some still assigned to them both the same value, while Mendeleeff did not hesitate to invert the order by making Co = 58·5 and Ni = 59. After taking into account all the best evidence on the subject, it appears certain that the atomic weight of cobalt is greater than that of nickel, but the fact remains that the values differ from each other by an amount which is less than the difference between any other two well established atomic weights, the respective numbers being variously represented by different authorities as follows :— The object of my experiments, however, soon developed into a wider field, for it appeared that the results obtained with these two metals might be made the means of further testing the validity of the law of Dulong and Petit, inasmuch as temperatures at which the specific heats would he determined are not only very remote, hut about equally remote, from the melting points of these two metals. Both metals are now obtainable in a pure state, and after melting and solidification under the same conditions are presumably in the same state of aggregation. Their atomic weights, though not known exactly, are undoubtedly very near together, as are also the densities of the metals and other of their physical properties.

scholarly journals II. The specific heats of metals and the relation of specific heat to atomic weight.—Part II

1903 ◽  
Vol 201 (331-345) ◽  
pp. 37-43 ◽  
Keyword(s):  
Specific Heat ◽  
Boiling Point ◽  
Atomic Weight ◽  
Liquid Oxygen ◽  
Specific Heats ◽  
Pure Cobalt ◽  
Total Range ◽  
Weight Part ◽  
Cobalt And Nickel

In the Bakerian Lecture for 1900 (‘Phil. Trans.,' A, vol. 194, p. 233) it was shown that the specific heats of very pure cobalt and nickel, when compared at temperatures from 100°C. down to the boiling-point of liquid oxygen, — 182°.5 C., steadily approach each other and together tend towards a least value which is at present unknown. It was thought desirable to increase the number of determinations at successive points on the thermometric scale, and to extend the total range of the experiments so as to afford better data for calculation of the form of the curves. The following is an account of the results obtained.

scholarly journals XIV. On the Specific Heat of the Gases

1826 ◽  
Vol 10 (1) ◽  
pp. 195-216
Author(s):  
W. T. Haycraft
Keyword(s):  
Specific Heat ◽  
Royal Society ◽  
The Public ◽  
Specific Heats ◽  
Limited Degree ◽  
The Subject

The experiments which I now submit to the Royal Society are repetitions of those I made many months ago, for the purpose of ascertaining the Specific Heats of the Gases. The importance of the subject so impressed my mind, that I determined to spare no pains in the prosecution of the inquiry, and therefore I willingly withheld my first experiments from the public eye, until, by a fresh series, I might present them with the greater confidence. The apparatus employed in these experiments was calculated to operate upon greater quantities of the Gases than the former one, and as every precaution which had been suggested was adopted, they have, perhaps, given even more decisive results than the last. The results themselves, however, are in every important particular exactly the same. It is also but justice to myself to state, that the conclusions which the former experiments led to, were exactly the reverse of what I had anticipated, and that they seemed at the time totally opposed to the doctrines of Black and Crawford, which I am still disposed to credit to a limited degree.

scholarly journals VI. The specific heats of metals and the relation of specific heat to atomic weight.—Part III

1904 ◽  
Vol 203 (359-371) ◽  
pp. 139-149 ◽  
Keyword(s):  
Specific Heat ◽  
Atomic Weight ◽  
The Other ◽  
Influence Of Temperature ◽  
Specific Heats ◽  
Weight Part ◽  
Chemical Combination ◽  
Influence Of Temperature On ◽  
The Mean ◽  
The One

The law of Neumann assumes that when an atom enters into chemical combination it retains the same capacity for heat as when in the uncombined or elemental state. This generalisation is, however, based on the values observed for the mean specific heats of elements and their compounds between 0° and 100° C. Attention was directed in Part II. of this investigation to the great differences found in the influence of temperature on the specific heats of various metals, such as aluminium on the one hand, and silver or platinum on the other. The experiments now about to be described were undertaken with the object of ascertaining to what extent these differences persist in the compounds of such elements.

scholarly journals II. Investigations of the specific heat of solid and liquid bodies

1864 ◽  
Vol 13 ◽  
pp. 229-239 ◽  
Keyword(s):  
Specific Heat ◽  
Atomic Weight ◽  
The Subject ◽  
Solid Bodies

In the first part the author discusses the earlier investigations on the specific heat of solid bodies, and on the relations of this property to their atomic weight and composition. In this historical report he gives a com­plete analysis of the various opinions published on the subject.

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.

scholarly journals The specific heats of metals and the relation of specific heat to atomic weight. Part II

1903 ◽  
Vol 71 (467-476) ◽  
pp. 220-221 ◽  
Keyword(s):  
Specific Heat ◽  
Atomic Weight ◽  
Absolute Zero ◽  
Nickel Steel ◽  
Pure Aluminium ◽  
Specific Heats ◽  
Nickel Cobalt ◽  
Weight Part ◽  
The Mean ◽  
Atomic Heat

The following values have been obtained for the mean specific heats, of pure aluminium, nickel, cobalt, silver, and platinum, within the several limits of temperature indicated: From these results the specific heats at successive temperatures on the absolute scale have been calculated, and it appears that the assumption of a constant atomic heat at absolute zero is untenable. The mean specific heat of a sample of nickel steel, containing 36 percent, of nickel and having remarkably small dilatation, was found to be as follows.

II. Note on the atomic weight of glucinum or beryllium

1883 ◽  
Vol 35 (224-226) ◽  
pp. 248-250
Keyword(s):  
Specific Heat ◽  
Atomic Weight ◽  
Minute Quantity ◽  
The Difference ◽  
Atomic Heat

In the course of a paper by Professor Humpidge on the above subject, recently read before the Society, the author seeks to decide between the atomic weight 9·2 for beryllium, resulting from my comparison of the atomic heat of the element with that of silver and aluminium, and the value 13·8, arrived at by MM. Nilson and Pettersson by determination of specific heat.J The difference between the two possible atomic weights is so small, and the difficulties met with in attempting to prepare even a few decigrams of beryllium are so great, that both sets of experiments have been objected to on the ground, amongst others, that the metal employed was in all cases impure. My specimen admittedly contained a minute quantity of platinum, and the Proportion of known impurity in one of MM. Wilson and Pettersson's specimens reached 13 per cent. Unfortunately, Professor Humpidge's metal though claimed to be the purest yet prepared, is shown by analysis to be rather less pure than one of the specimens employed by Nilson and Pettersson, hence the experiments lately made known to the Society do not carry the inquiry beyond the point previously reached, save in one noteworthy particular, namely, that there appears to be a considerable, though irregular, rise in specific heat of the element as the proportion of impurity diminishes; but the value is still much below that required for the atomic weight 9·2. Thus for a specimen of beryllium which contained 13 per cent. of known of impurity Wilson and Pettersson obtained the specific heat 0·4084 between 0° and 100° C., and for a less impure specimen 0·425; while Professor Humpidge, in one of his experiments with a material that contained 6 per cent, of impurity, found the specific heat to be nearly 0·45 (0·4497). In all these cases corrections were applied which were believed to eliminate the effects due to the impurities known to be present—in part mechanically mixed with the metal and partly alloyed with it.

On the method of condensation in calorimetry

1887 ◽  
Vol 41 (246-250) ◽  
pp. 352-371 ◽  
Keyword(s):  
Specific Heat ◽  
Latent Heat ◽  
Experimental Verification ◽  
Direct Determination ◽  
Constant Volume ◽  
Specific Heats ◽  
The Subject

This paper is devoted generally to experimental verification of a method of condensation applied to the determination of specific heat. The extension of the method to the calorimetry of latent heat of gasification has been the subject of some experiments, but the further delay necessary to complete these compels me to defer their consideration. Similarly its application, theoretically practicable, to the direct determination of the specific heats of gases at constant volume, is not here considered. In another paper (p. 250) some results bearing on the possible value of the method in physical mineralogy and in determinative mineralogy are given. The method was originally devised in the hope that it might be of service in this branch of investigation.

scholarly journals XIII. Reply to a note by Professor J. E. Reynolds on the atomic weight of glucinum or beryllium

1883 ◽  
Vol 35 (224-226) ◽  
pp. 358-359
Keyword(s):  
Specific Heat ◽  
Atomic Weight ◽  
Specific Heats

In the above-mentioned note of Professor Reynolds the author criticises the results detailed in a paper which I recently had the honour to contribute to the Society, and draws an inference from the specific heats of different specimens of the metal which I cannot admit to be founded on facts. Professor Reynolds remarks that all the results obtained by Nilson and myself tend in one direction, viz., to a considerable, though irregular, rise in the specific heat as the impurities diminish.

scholarly journals Discussion on isotopes

1921 ◽  
Vol 99 (697) ◽  
pp. 87-104 ◽  
Keyword(s):  
Outer Layer ◽  
Chemical Properties ◽  
Residual Effect ◽  
Atomic Weight ◽  
The Core ◽  
History Of ◽  
The Subject ◽  
The Difference ◽  
Layer I ◽  
Special Points

Sir J. J. Thomson: I think I shall best open the discussion this afternoon if, instead of attempting a history of the subject of isotopes, I confine myself to a few special points. The conception of isotopes—that is, of two elements which have different atomic weights but chemical properties so closely resembling each other that they have not yet been separated by chemical methods—was, I believe, first reached by Prof. Soddy in connection with radio-active substances. In the few remarks which I have to make this afternoon, I shall not deal with these substances; I will leave them to others who are better acquainted with them than myself; I propose to confine myself to the consideration of the isotopes, or with some points connected with the isotopes, of the lighter elements. Before doing so, I should like to say just a word about the conception of isotopes on the electron theory of an atom. On that theory the atoms of the isotopes contain an equal number of electrons. The difference in the atomic weight is supposed to be due to the simultaneous entry into the core of the atom of one or more positive charges, and an equal number of electrons, so that the electric charge on the core is not affected. In reference to this, I would like to say that it by no means follows that an electron and a positive charge will neutralise each other at the distances that occur in the atom, however close together they might be placed; and, though one would expect that the residual effect would not be large, yet I think it might easily be appreciable, and might produce some difference between the properties, chemical or physical, of the isotopes. For example, though I do not think it would affect the number of electrons in the outer layer, I think it would affect the distance of the outer layer from the core of the atom. And the statement that the chemical properties of an element depend only on the outer layer of the atom, is one with which I should agree if it is recognised that, even if the number of electrons in the outer layer is unaltered, differences in the distance of this layer from the centre may result in different chemical properties. For example, we, or at any rate some of us, believe that the valency of an element fixes the number of electrons in the outer layer. Thus, there are the same number of electrons in the outer layer of the atoms of silicon and of carbon, and yet there are well-marked differences in the chemical properties of these two substances.

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