scholarly journals Some adsorption isothermals for a plane platinum surface

1929 ◽  
Vol 122 (790) ◽  
pp. 487-497 ◽  
Keyword(s):  
Adsorption Layer ◽  
Chemical Heterogeneity ◽  
Surface Films ◽  
Platinum Surface ◽  
Homogeneous Surface ◽  
Direct Technique ◽  
Chemical Combination ◽  
Great Ease ◽  
Metal Filament ◽  
The Subject

Quantitative experiments to establish the isothermals of adsorption on nonporous surfaces have only rarely been undertaken, owing mainly, no doubt, to the obvious difficulty of measuring the small absolute adsorptions on surfaces of manageable size. Yet it can well be held that many, if not all, of the uncertainties still attaching to the mechanism of adsorption and the constitution of the adsorption layer depend not upon any inherent complexity in the process itself, but upon the complicated geometrical and chemical con­ditions existing in the accessible surfaces of the porous materials, such as charcoal, that have so often been the subject of study. Moreover, it is by no means easy to determine in many cases what parts of the total “sorption” are due to adsorption, solid solution, or even chemical combination. McBain has emphasised the sensitiveness of the course of adsorption to the progressive removal of chemical heterogeneity from a porous surface. Some applications of the electric coherer to adsorption problems have been described in former communications; it may perhaps be appropriate to recall the main advantages that the method appears to possess over the more direct technique in common use; ( a ) the adsorption takes place on the non-porous and chemically homogeneous surface of a fine metal filament, that can be submitted to heat treatment electrically with great ease; ( b ) there is an immediate and direct test of the “bareness” of the surface, quite independently of the subsequent adsorption experiments; ( c ) from the nature of the technique only true surface films play any part in the measurements. The principal disadvantage is that the adsorbed amount is measured by the critical cohering voltage instead of directly, but this difficulty can be surmounted in the follow­ing way.

scholarly journals The Issue of the Free Surface of Adsorbent in the Description of a Monolayer Mobile Gas Adsorption on Solids

2019 ◽  
Vol 69 (4) ◽  
pp. 33-44
Author(s):  
Jerzy K. Garbacz ◽  
Jerzy Ciechalski ◽  
Mariusz Kozakiewicz
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Theoretical Basis ◽  
Adsorption Layer ◽  
Gas Adsorption ◽  
Adsorption Equilibrium ◽  
Critical Parameters ◽  
Two Dimensional ◽  
Homogeneous Surface ◽  
Adsorption Equation

AbstractThis paper characterises the concept of monolayer mobile gas adsorption on a homogeneous surface of a solid. The theoretical basis of the phenomenological variant of the description of adsorption equilibrium in the system in question are discussed. The essential features of the solutions to date are discussed, and the effect of the free surface of adsorbent on the form of the final adsorption equation is stressed.An alternative concept of the free surface based on the modified two-dimensional analogue of Reiss, Frisch and Lebowitz equations is also presented. The obtained adsorption equation was tested for critical parameters of two-dimensional condensation of the adsorption layer, and then used to describe the experimental data available in literature. The verification carried out confirmed the correctness and usefulness of the proposed concept.

III. Researches on refraction-equivalents

1868 ◽  
Vol 16 ◽  
pp. 439-444 ◽  
Keyword(s):  
Refractive Index ◽  
Good Deal ◽  
Symbolic Language ◽  
Chemical Combination ◽  
The Subject ◽  
Condition Solution ◽  
Minus Unity

Since the paper of the Rev. T. Pelham Dale and myself “On the Refraction, Dispersion, and Sensitiveness of Liquids our researches have been continued from time to time, and a good deal of attention has been paid to the subject in Germany. The permanence of the specific refractive energy of a body, notwithstanding change of temperature, aggregate condition, solution, or even chemical combination, has been confirmed, and upon this has been built the doctrine of Refraction-equivalents. Our specific refractive energy is the refractive index of any substance minus unity, divided by the density; in symbolic language µ –1/ d . Professor Landolt’s “Refraction-equivalent” is the same multiplied by the chemical equivalent, or P µ –1/ d .

scholarly journals Magnetism and atomic structure.—II. The constitution of the hydrogen-palladium system and other similar systems

1922 ◽  
Vol 101 (710) ◽  
pp. 264-279 ◽  
Keyword(s):  
Diamagnetic Susceptibility ◽  
Molecular Form ◽  
Surface Adsorption ◽  
Palladium Black ◽  
Previous Knowledge ◽  
Complex Process ◽  
Surface Condensation ◽  
Chemical Combination ◽  
The Subject ◽  
Molecular Forces

The present work is a continuation of that published in ‘Phil. Trans., A, vol. 214, pp. 109-146 (1914); A, vol. 215, pp. 79-103 (1915); A, vol. 220, pp. 247-289 (1920); ‘Roy. Soc. Proc.,' A, vol. 95, p. 58 (1918), and A, vol. 98, p. 264 (1921). It was believed that a magnetic examination of the properties of palladium black which had been charged with hydrogen would enable us to decide which of the proposed constitutions is the correct one. If the hydrogen were in the atomic state and free , one might expect that the system would be more magnetic than uncharged palladium black, whether the assumed constitution of the hydrogen atom be that of Bohr or that proposed by the author. If the contained hydrogen were in the molecular form, either in the state of a gas or condensed to a liquid, since gaseous and liquid hydrogen are both diamagnetic, we should expect a diminution of the magnetic property of the system by a small amount, depending on the minute diamagnetic susceptibility of molecular hydrogen and the amount of gas occluded. Lastly, if the hydrogen enters into combination with the palladium, or is associated with the palladium so as to form a type of loose chemical compound, we should, in the light of previous knowledge of the effects of chemical combination on magnetic susceptibility, expect a change depending on the nature of the compound formed. It is impossible here to go into details regarding the vast amount of work which has been undertaken to solve the problem of gaseous occlusion. Reference is made to the General Discussion held by the Faraday Society on the subject. It will be convenient to summarise here the diverse views at present held as to the nature of the complex process of occlusion. These have been given by A. W. Porter under the following six heads:— (1) Chemical combination of the gas with the metal. (2) Simple solid solution, either separately or in conjunction with (1). (3) Two solid solutions in contiguous phases. (4) Solution accompanied by surface adsorption. (5) Surface condensation under molecular forces unaccompanied by solution. (6) Simple inclusion of the gas in the interstices of the metal.

scholarly journals Absorption of helium and other gases under the electric discharge

1912 ◽  
Vol 87 (596) ◽  
pp. 381-384 ◽  
Keyword(s):  
Electric Discharge ◽  
Definite Evidence ◽  
Chemical Combination ◽  
The Subject ◽  
Silent Electric Discharge ◽  
Carbon Bisulphide

Berthelot announced in 1896 that he had succeeded in observing an absorption of argon, and later of helium, when these gases were submitted to the silent electric discharge, in the presence of either benzene or bisulphide of carbon: further, that the gases could be extracted by heat from the solid substances deposited on the walls of the vessel. The experiments were regarded as proving that argon and helium were after all capable of entering into chemical combination. I shall confine discussion to the supposed interaction of helium and carbon bisulphide. Berthelot obtained more definite results with this reagent than with benzene. At the time they were published, these accepted, and, so far as I have been able to learn, they have not been more favourably regarded since. Berthelot, however, adhered to them in his ‘Traité Pratique de l’Analyse des Gaz,’ published in 1906, about the time of his death, and other experimenters have not produced definite evidence against them. The subject cannot be considered unimportant, and I have long felt that the experiments ought to be repeated. This has now been done, with results altogether negative.

scholarly journals I. The ionisation produced by hot platinum in different gases

1908 ◽  
Vol 207 (413-426) ◽  
pp. 1-64 ◽  
Keyword(s):  
Kinetic Energy ◽  
Water Vapour ◽  
Metallic Surface ◽  
Present Communication ◽  
Abnormal Behaviour ◽  
Platinum Surface ◽  
Positive Ions ◽  
Wide Range ◽  
The Subject ◽  
Different Gases

The principal objects of this investigation have been to examine the part played by the surrounding gas in the production of ions by hot metals and to discover, if possible, the mechanism by which the positive ions originate. In what follows, previous work on ionisation by hot metals will not be described, except in so far as it bears directly on the questions investigated, since the historical part of the subject has been fully treated in previous papers by the writer, and others. The present communication deals chiefly with the emission of positive ions from hot platinum, as earlier work has yielded much more information concerning the negative ionisation. In 1901 the writer showed that a great number of facts in connection with the negative ionisation from hot metals could be explained by supposing that the electrons, of which the ions consist, were produced in the metal itself, from which they escaped by virtue of their kinetic energy. This theory makes the negative ionisation a function only of the metal surface and its temperature, and therefore independent of the nature and pressure of the surrounding gas, except in so far as this may have the effect of modifying the nature of the metallic surface. H. A. Wilson has confirmed this part of the theory by showing that the negative leak, except when ionisation by collision occurs, has the same value in air, nitrogen, and water vapour over a wide range of pressures. Wilson also showed, however, that hydrogen greatly modifies the negative leak. The experiments in the present paper seem to show that the effect of hydrogen is due to some change it produces in the platinum surface; its abnormal behaviour is probably bound up with its electropositive character.

scholarly journals III. On evaporation and dissociation.—Part III. A study of the thermal properties of ethyl oxide

1887 ◽  
Vol 178 ◽  
pp. 57-93 ◽  
Keyword(s):  
Thermal Properties ◽  
Ethyl Alcohol ◽  
Vapour Pressure ◽  
Chemical Combination ◽  
Thermal Constants ◽  
Similar Series ◽  
Vapour Density ◽  
The Subject ◽  
Density Expansion

In a memoir published in the Royal Society’s ‘Philosophical Transactions,’ 1886 (Part I.), p. 123, “On the Thermal Properties of Ethyl Alcohol,” we gave the results of a research on the vapour-pressures of alcohol, the densities of its vapour—both unsaturated and saturated—and the expansion and compressibility of liquid alcohol at various temperatures; and from these data were deduced the amounts of heat required to vaporize alcohol at those temperatures. Our object in these researches has been to compare carefully the behaviour of stable with that of unstable bodies, and, if possible, to acquire some clear ideas of the nature of chemical combination. But, as the properties of stable bodies are still to a great extent unknown, we have deemed it advisable to extend our research with the view of investigating this relationship; and for that purpose we have made a similar series of measurements of the thermal constants of ethyl oxide (C 2 H 5 ) 2 O. The data, and the deductions from the data, are the subject of the following memoir. Experiments on the vapour-pressure, vapour-density, expansion, and other properties of ether have been made by Regnault, Kopp, Pierre, Mendelejeff, Avenarius, and others, and their results shall be quoted when necessary.

scholarly journals V. Gold-aluminium alloys

1900 ◽  
Vol 194 (252-261) ◽  
pp. 201-232 ◽  
Keyword(s):  
Aluminium Alloys ◽  
Freezing Point ◽  
Chemical Compounds ◽  
Chemical Society ◽  
Rapid Analysis ◽  
Chemical Combination ◽  
Point Curve ◽  
The Subject ◽  
The One

This paper is a study of the binary alloys composed of gold and aluminium. The fact that metals in many cases form definite chemical compounds with each other, is becoming increasingly evident as attention is given to the subject. But there are many pairs of metals whose freezing point-curve affords no indication of chemical combination, and which probably do not combine with each other under the conditions of our experiments. It is therefore desirable, in seeking for such compounds, to select a pair of metals which are known to have a peculiar relation to each other. We chose gold and aluminium for several reasons. First, on account of the beautiful purple compound of Sir W. Roberts-Austen, and on account of our own experiments (‘Journal Chemical Society/ vol. 74, 1894), which showed it to be a very stable body in solution. There was also the important point that the alloys of gold and aluminium admit of fairly rapid analysis by the determination of the gold. In the present paper the freezing point method is combined with a microscopic study of the alloys, and we hope that it will be found that the interpretation of the results is more conclusive than in previous papers of our own and of others in which only the one method or the other was employed.

scholarly journals VI. On the heat dissipated by a platinum surface at high temperatures. Part IV. Thermal emissivity in high-pressure gases

1901 ◽  
Vol 197 (287-299) ◽  
pp. 229-254 ◽  
Keyword(s):  
Atmospheric Pressure ◽  
High Pressures ◽  
Unit Length ◽  
Electrical Energy ◽  
Perfect Gas ◽  
Platinum Surface ◽  
Thermal Emissivity ◽  
The Subject ◽  
Rate Of Cooling ◽  
Energy Dissipated

The question of the heat dissipated by a hot body in gases at ordinary pressures has received considerable attention during recent years. The subject has been experimentally treated in many different ways. The rate of cooling of a body of known specific heat has been directly measured by Dulong and Petit, Narr, Macfarlane, Nichol, Stefan, Brush, Bottomley, Winkelmann, Kundt, and Warburg, Eckerlein, Graetz, &c. By Christiansen’s method, the value of the conductivity has been derived from the fall of temperature per unit length along the axis of a cylinder carrying a constant flow of heat. Schleierm acher, Sala, Ayrton, and others have preferred to measure the quantity of electrical energy dissipated per unit time. These experiments have, however, been carried out at or below the atmospheric pressure, and the question of the heat dissipated in gases at high pressures has rarely been touched upon. From the ordinarily accepted principles of the Kinetic theory of gases, it may be shown that the conductivity of any perfect gas is independent of pressure. The experimental work of Stefan and of Kundt and Warburg has gone far to confirm this law as far as ordinary pressures are concerned. It will be seen, however, that at higher pressures, only a small proportion of the loss of heat is due to conductivity, and the question as to whether the theoretical law is strictly correct, though well worth investigation, is not of primary importance. For the above reasons the present work has been restricted to a study of the total heat dissipated at exceptionally high pressures and temperatures.

Load-Bearing Ordered Intermetallic Compounds—A Historical View

MRS Bulletin ◽  
1991 ◽  
Vol 16 (5) ◽  
pp. 18-23 ◽  
Author(s):  
Robert W. Cahn
Keyword(s):  
Intermetallic Compounds ◽  
Size Factor ◽  
Physical Metallurgy ◽  
Linus Pauling ◽  
Historical View ◽  
Chemical Combination ◽  
Ordered Intermetallic ◽  
Long Time ◽  
The Subject ◽  
Chemical Anomalies

Chemical combination among metals has been studied for a long time. In the early days, chemists had much difficulty in understanding how metals could combine at all among themselves, often in several different proportions, since this often seemed to be at variance with elementary notions of valency. Indeed, in the last century a distinction was proposed between daltonides and berthollides, the former being compounds with simple ratios of the numbers of constituent atoms… consistent with Dalton's atomic theory!… the latter, called after a skeptical French chemist, being the name reserved for compounds with a wide composition range which scarcely seemed explicable on any reasonable atomic model. A few nostalgic souls still employ these distinctions.An early classic on the subject was a book published by two Italian chemists in 1918. British metallurgist C.H. Desch also wrote a monograph on intermetallic compounds in 1914 (the year when the name “physical metallurgy” was first proposed, and the chemical bias of metallurgy shifted toward a physical one), and he declared that “attempts to form a theory of the constitution of intermetallic compounds… have been comparatively unsuccessful.” When he returned to the subject 20 years later, he felt much more cheerful about the state of the theory because in the meantime Hume-Rothery had introduced the concepts of atomic size factor, electron/atom ratio, and electronegativity (a concept also associated with the name of Linus Pauling) into the discussion of intermetallic phases, or compounds. Today, a battery of sophisticated physical concepts is used to make sense of both binary and multielement intermetallic compounds and they are no longer regarded as chemical anomalies.

Ultrasound Treatments in Degassed Water

1992 ◽  
Vol 1 (4) ◽  
pp. 284-289 ◽  
Author(s):  
George Forrest ◽  
Kurt Rosen
Keyword(s):  
Therapeutic Range ◽  
Direct Contact ◽  
Skin Surface ◽  
Extensor Tendons ◽  
Effective Form ◽  
Direct Technique ◽  
Immersion Technique ◽  
Before And After ◽  
The Subject ◽  
Methods Of Application

Ultrasound is a commonly used modality of deep heating. Two techniques of application have been recommended: a technique in which the applicator head is applied directly to the subject and an immersion technique, The purpose of this study was to determine whether ultrasound treatments using the immersion technique in degassed water are as effective as ultrasound treatments using the direct technique of application in raising the temperature of periarticular structures into the therapeutic range. The limbs of a pig were treated with the direct and immersion techniques of application. Temperatures of the skin surface and of the extensor tendons of the ankle were taken before and after both methods of application. Treatments with the applicator head in direct contact with the limb of the subject were the more effective form of heating.

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