scholarly journals VII. On the specific heats of gases at constant volume.—Part III. The specific heat of carbon dioxide as a function of temperature

1894 ◽  
Vol 185 ◽  
pp. 961-981
Keyword(s):  
Carbon Dioxide ◽  
Critical Temperature ◽  
Specific Heat ◽  
Lower Limit ◽  
Latent Heat ◽  
Large Scale ◽  
Initial Temperature ◽  
Specific Heats ◽  
Upper Limit ◽  
Points Of Interest

The question of the dependence of the specific heat of carbon dioxide upon its density having been investigated, so far as is described in Part II., the further question remained over as to whether the specific heat of a gas is dependent upons range of temperature over which the gas is heated. The question was evidently within the power of the steam calorimeter to answer, provided arrangements were ride for varying the lower limit of temperature—the initial temperature. To vary upper limit by resorting to vapours other than steam would, on the large scale on which operations were being conducted, have been costly and troublesome, though not attended with any inaccuracy, as the experiments of Wirtz on the Heats of several vapours, determined by the method of condensation, appear show. It is to be observed, indeed, that the use of vapours other than water would .ow of operations being conducted upon smaller quantities of the gas, as it would be sy to find liquids whose vapours possessed a latent heat one-half or one-fourth as eat as that of water; and a construction necessitating but little loss of vapour at experiment could be easily contrived. In this case, also, it would be necessary provide a means of varying the initial temperature. Chiefly on the grounds of supense I decided upon the use of steam in conjunction with a means of altering the initial temperature. It appeared probable, too, that the alteration of the initial temperature between 10° and 100° would disclose the chief points of interest in these of the gas under consideration, the critical temperature lying within this range.

I. On the specific heats of gases at constant volume. Part II. Carbon dioxide

1894 ◽  
Vol 55 (331-335) ◽  
pp. 390-391 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Specific Heat ◽  
Lower Limit ◽  
Liquid State ◽  
Thermal Effects ◽  
Constant Volume ◽  
Specific Heats ◽  
Absolute Density ◽  
The Mean ◽  
True Specific Heat

In the former experiments on this gas, recorded in the first part of this research, the highest absolute density at which the specific heat was determined was 0·0378. In the present observations the determinations of specific heat have been carried to densities at which the substance was partly in the liquid state at the lower limit of temperature of the experiments. Observations dealing with true specific heat, uncomplicated by the presence of thermal effects due to the presence of liquid, are limited by the density 0·1444. At this density the mean specific heat over the range, 12° C. to 100° C., is 0·2035.

II. On the specific heats of gases at constant volume. Part III. The specific heat of carbon dioxide as a function of temperature

1894 ◽  
Vol 55 (331-335) ◽  
pp. 392-393
Keyword(s):  
Carbon Dioxide ◽  
Specific Heat ◽  
Atmospheric Pressure ◽  
Initial Temperature ◽  
Constant Volume ◽  
Specific Heats

In order to investigate the question of the variation of the specific heat of carbon dioxide with temperature, a steam calorimeter was constructed having double walls of thin brass, between which the vapour of a liquid boiling under atmospheric pressure could be circulated. The vessels used in the experiments were hung in the closed inner chamber. Into this chamber steam could be admitted after the temperature had become stationary and the same as that of the jacketting vapour. In this way the initial temperature could be varied.

scholarly journals XVI. On the specific heats of gases at constant volume.—Part II. Carbon dioxide

1894 ◽  
Vol 185 ◽  
pp. 943-959 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Specific Heat ◽  
Constant Volume ◽  
Specific Heats ◽  
Extended Range ◽  
Absolute Density ◽  
Lower Temperature ◽  
The One ◽  
Range Observation ◽  
Linear Nature

The present paper is occupied with an experimental investigation into the variation of the specific heat at constant volume of carbon dioxide attending change of absolute density. The investigation is in continuation of a previous one, in which Carbon Dioxide, Air, and Hydrogen were the subjects of a similar enquiry over low ranges of density. It appeared to me desirable to extend the observations more especially in the case of carbon dioxide, because of the extended knowledge we already possess of its isothermals, and the fact that its critical temperature is within convenient reach. Other physical properties of the gas have also received much attention of recent years. It is also readily procured in a nearly pure state. The observations recorded in this paper extend, in the one direction, to densities, such that liquid is present at the lower temperature; and in the other, to a junction with the highest densities of the former paper. A plotting of the new observations is in satisfactory agreement with the record of the old. It reveals, however, the fact that the linear nature of the variation of the specific heat with density, deduced from the former results, is not truly applicable over the new, much more extended range observation. For convenience the chart at the end of this paper embraces the former results, and the present paper is extended to include the entire results on the variation of specific heat with density where the range of temperature, obtaining at each experiment, is approximately the same: that from air temperature to 100° C.

THE VISCOSITY OF CARBON DIOXIDE IN THE CRITICAL REGION

1940 ◽  
Vol 18b (10) ◽  
pp. 322-332 ◽  
Author(s):  
S. N. Naldrett ◽  
O. Maass
Keyword(s):  
Carbon Dioxide ◽  
Critical Temperature ◽  
Lower Limit ◽  
Critical Region ◽  
Liquid State ◽  
Condensation Temperature ◽  
Constant Density ◽  
Time Lags ◽  
Great Precision ◽  
Temperature Time

Measurements of the viscosity of carbon dioxide in the critical region have been made with great precision by means of an oscillating disc viscosimeter. The variation of viscosity with temperature at constant density has been determined for 14 different densities. Isothermals have been evaluated from a plot of the isochores. One isothermal was determined directly and is in agreement with those determined indirectly.The form of the viscosity-temperature isochores is not the same as that found by Mason and Maass (12) for ethylene, in that there is no minimum at the critical temperature nor even up to 7 °C. above. For the region just above the condensation temperature, the viscosity is more dependent on density than on temperature; the isochores are almost flat and are well separated. However, the isothermals are spread between an upper and a lower limit of density, showing that viscosity is not entirely independent of temperature. Time lags were observed in the present investigation in the opposite direction to those observed by Geddes and Maass (9); this would appear to decrease the strength of their claims that the time lags that they observed are due to the formation of a structure in the liquid state.

scholarly journals The determination of the specific heat of gases at high temperatures by the sound velocity method II—Carbon dioxide

1936 ◽  
Vol 156 (889) ◽  
pp. 504-517 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Specific Heat ◽  
Sound Velocity ◽  
Quartz Crystal ◽  
Wave System ◽  
Sound Waves ◽  
Heated Tube ◽  
Specific Heats

In a previous paper an account was given of experiments to determine the specific heats of carbon monoxide up to a temperature of 1800° C. by the sound velocity method. The principle of the method employed was the setting up in a heated tube of a stationary train of sound waves; the source of the wave system being a quartz crystal vibrating piezo-electrically at a known frequency.

The specific heats below 320°K of potassium, rubidium and caesium

1965 ◽  
Vol 284 (1396) ◽  
pp. 83-107 ◽  
Keyword(s):  
Melting Point ◽  
Specific Heat ◽  
Latent Heat ◽  
Slow Release ◽  
Heat Of Fusion ◽  
Additional Contribution ◽  
Thermal Generation ◽  
Latent Heat Of Fusion ◽  
Specific Heats ◽  
Increasing Temperature

The specific heat of potassium has been measured in the range 0·4 to 26°K and the specific heats of rubidium and caesium in the range 0·4 to 320°K. Previously reported specific heat anomalies in the range 100 to 300°K were not confirmed. The θ c 0 and γ values were estimated as 90·6 +1·4 -0·3 °K and 497 ± 20 μ cal degK -2 gatom -1 for potassium, as 55·6 ± 0·5°K and 576 +70 -40 μ cal degK -2 gatom -1 for rubidium and as 38·4 ± 0·6°K and 764 ± 250 μ cal degK -2 gatom -1 for caesium. A slow release of energy (~ 1 μ cal s -1 gatom -1 ), dependent on thermal history, was observed from rubidium and caesium in the region of 4°K and may correspond to the annealing out of defects introduced by plastic strain on cooling. Positive anharmonic contributions to the specific heat are evident at high temperatures and an additional contribution to the specific heat, of the form (e - E / RT /T 2 ), becomes apparent from about 50°K below the melting point and may be identified with the thermal generation of lattice vacancies. The melting point of pure rubidium is estimated as 312·65 ± 0·01°K and the latent heat of fusion as 524·3 ± 1·0 cal/gatom. For caesium the melting point is 301·55 ± 0·01°K and, with some assumptions, the latent heat is 498·9 ± 0·5 cal/gatom. For both metals the specific heat of the liquid decreases with increasing temperature.

The Specific Heat of Carbon Dioxide—Correction

1928 ◽  
Vol 24 (2) ◽  
pp. 290-290
Author(s):  
W. H. McCrea
Keyword(s):  
Carbon Dioxide ◽  
Specific Heat ◽  
Low Temperatures ◽  
Molecular Form ◽  
Specific Heats ◽  
Heat Curve

In a recent paper in these Proceedings the writer suggested the possibility of a transition from one molecular form to another in CO2. The suggestion is embodied in the equation (10) and the resulting specific heats for low temperatures given. He greatly regrets that it was not till after those results were published that he found they gave a high and altogether impossible maximum in the specific heat curve for higher temperatures before it returns to the neighbourhood of the unmodified curve Cv′.

scholarly journals III. On the specific heats of gases at constant volume. Part I. Air, carbon dioxide, and hydrogen

1891 ◽  
Vol 48 (292-295) ◽  
pp. 440-441 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Specific Heat ◽  
Mean Value ◽  
Constant Volume ◽  
Specific Heats ◽  
Absolute Density ◽  
The Mean ◽  
The Absolute

In this first notice the specific heats, at constant volumes, of air, carbon dioxide, and hydrogen are treated over pressures ranging from 7 to 25 atmospheres. The range of temperature is not sensibly varied. It is found that the specific heats of these gases are not constant, but are variable with the density. In the case of air the departure from constancy is small and positive; that is, the specific heat increases with increase of the density. The experiments afford directly the mean value 0·1721 for the specific heat of air at the absolute density of 0·0205, corresponding to the pressure of 19·51 atmospheres. A formula based on the variation of the specific heat with density observed in the experiments ascribes the value 0·1715 for the specific heat at the pressure of one atmosphere.

Order?Disorder Transformations in Alloys. The Inclusion of Non-nearest Neighbour Interactions in Cluster Variation Methods. II. Low Temperature Specific Heats for Body Centred Cubic Lattices

1981 ◽  
Vol 34 (1) ◽  
pp. 75 ◽  
Author(s):  
Joan M Hanley ◽  
Thomas E Peacock
Keyword(s):  
Critical Temperature ◽  
Low Temperature ◽  
Specific Heat ◽  
Interaction Energy ◽  
Cluster Variation Method ◽  
Variation Method ◽  
Nearest Neighbour ◽  
Specific Heats ◽  
Low Temperature Specific Heat ◽  
Cluster Variation

In Part I, the Sanchez and de Fontaine formulation of the cluster variation method was used to study the dependence of the critical temperature and the high temperature specific heat on the ratio of second neighbour to nearest neighbour interaction energy. This method can be extended to find solutions for the ordered state. The dependence of the low temperature specific heat on the interaction energy ratio is studied. As with the critical temperature and high T specific heat studies, it is found that both the sign and magnitude of ex affect the low temperature specific heat.

Regulation of Cerebral Autoregulation by Carbon Dioxide

2015 ◽  
Vol 122 (1) ◽  
pp. 196-205 ◽  
Author(s):  
Lingzhong Meng ◽  
Adrian W. Gelb
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Lower Limit ◽  
Cerebral Autoregulation ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Published Data ◽  
Rightward Shift ◽  
Blood Flows ◽  
Upper Limit

Abstract Cerebral autoregulation describes a mechanism that maintains cerebral blood flow stable despite fluctuating perfusion pressure. Multiple nonperfusion pressure processes also regulate cerebral perfusion. These mechanisms are integrated. The effect of the interplay between carbon dioxide and perfusion pressure on cerebral circulation has not been specifically reviewed. On the basis of the published data and speculation on the aspects that are without supportive data, the authors offer a conceptualization delineating the regulation of cerebral autoregulation by carbon dioxide. The authors conclude that hypercapnia causes the plateau to progressively ascend, a rightward shift of the lower limit, and a leftward shift of the upper limit. Conversely, hypocapnia results in the plateau shifting to lower cerebral blood flows, unremarkable change of the lower limit, and unclear change of the upper limit. It is emphasized that a sound understanding of both the limitations and the dynamic and integrated nature of cerebral autoregulation fosters a safer clinical practice.

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