On the effect of surrounding media on voltaic ignition

1851 ◽  
Vol 5 ◽  
pp. 783-784
Keyword(s):  
Platinum Wire ◽  
Philosophical Magazine ◽  
The Wire ◽  
The Difference ◽  
Different Gases

The author refers to some experiments of his published in the Philosophical Magazine for December 1845, and in the Bakerian Lecture for 1847, relating to the difference of ignition generated in a platinum wire heated by the voltaic current, when the wire is immersed in atmospheres of different gases. In the present paper these experiments are continued, the current being passed through two platinum wires both in the same voltaic circuit, but immersed in atmospheres of different gases. It appears from these experiments that the heat generated in the wire is less in hydrogen and its compounds than in other gases; and that when the wires and their atmospheres of gas are immersed in given quantities of water, the water surrounding the hydrogenous gases is less heated than that surrounding those which contain no hydrogen.

scholarly journals XIV.—On Torsional Oscillations of Wires

1900 ◽  
Vol 39 (2) ◽  
pp. 425-455
Author(s):  
W. Peddie
Keyword(s):  
Philosophical Magazine ◽  
Torsional Oscillations ◽  
Series Of Experiments ◽  
The Wire ◽  
The Difference ◽  
Image Position

This paper is in continuation of two others, on the same subject, previously communicated to the Society. In the First Paper (Philosophical Magazine, July 1894) it was shown that the formulawhere n, a, and b are constants in any one experiment, represents with accuracy the relation between y, the range of oscillation, and x, the number of oscillations which have taken place since torsion was first applied and the wire was left to itself, so that the oscillations gradually diminished. The apparatus employed, and the method of observation used, were identical with those described in the Second Paper above referred to. The wire which was experimented upon was the same as that used on the previous occasions. Its length, as given in the First and Second Papers, was 89·1 cm. A measurement made on the date 19.10.1897, in the course of the last series of experiments described in the present paper, showed that the length had become 89*3 cm. This increase was doubtless due to the fact that the heavy lead oscillator had been left attached to the wire during the whole of the intervening period. On the date given, it was also found that, with the same oscillator as was used in the experiments first described, ten oscillations were performed in 81 seconds, when the range was large, while 79 seconds were occupied when the range was small. This observation verified the result stated in the First Paper, that the period slightly increases as the range increases. It also showed that the wire was practically in the same condition as it was at first, in so far as elastic qualities are concerned; for the corresponding periods were only slightly less in earlier experiments, the difference being largely accounted for by the slight increase of length of the wire.

V. On the effect of surrounding media on voltaic ignition

1849 ◽  
Vol 139 ◽  
pp. 49-59
Keyword(s):  
Hydrogen Gas ◽  
Platinum Wire ◽  
Philosophical Magazine ◽  
Atmospheric Air ◽  
Specific Heats ◽  
The Wire

In the Philosophical Magazine for December 1845, I pointed out a striking differ­ence between the heat generated in a platinum wire by a voltaic current, according as the wire is immersed in atmospheric air or in hydrogen gas, and in the Bakerian Lecture for 1847 I have given some further experiments on this subject, in which the wire was ignited in atmospheres of various gases, while a voltameter enclosed in the circuit yielded an amount of gas in some inverse ratio to the heat developed in the wire. It was also shown, by a thermometer placed at a given distance, that the radiated heat was in a direct ratio with the visible heat. Although the phenomenon was apparently abnormal, there were many known phy­sical agencies by which it might possibly be explained, such as the different specific heats of the surrounding media, their different conducting powers for electricity, or the varying fluency or mobility of their particles which would carry off the heat by molecular currents with different degrees of rapidity.

scholarly journals I. The Bakerian Lecture. - On certain phenomena of voltaic ignition and the decomposition of water into its constituent gases by heat

1847 ◽  
Vol 137 ◽  
pp. 1-16 ◽  
Keyword(s):  
General Practice ◽  
Nitric Acid ◽  
Glass Tube ◽  
Platinum Wire ◽  
Pure Oxygen ◽  
Philosophical Magazine ◽  
The Wire ◽  
Decomposition Of Water ◽  
At Will

In the Philosophical Magazine for August 1841, I recommended for eudiometrical purposes, the use of a platinum wire ignited by a voltaic battery. In Plate I. fig. 1, is represented a form of apparatus for this purpose; it consists of a tube of Bohe­mian glass, with a loop of platinum wire 1/80th of an inch diameter sealed into its upper end; the size of the glass tube may be adapted to the quantity of gas sought to be analysed, and may when necessary be reduced to extremely small dimensions, one-eighth of an inch being ample; into this the gas may readily be made to ascend, by the insertion of a wire of copper, platinum, or glass, as may be suitable to the gas: two cells of the nitric-acid battery are sufficient fully to ignite the wire, and the same battery supplies, by electrolysis, pure oxygen and hydrogen for the analysis. Since the period when I first proposed this, I have seldom used any other apparatus for such gaseous analyses as are performed by combining the gas to be examined with oxygen or hydrogen. This eudiometer possesses the advantage of enabling the operator either to detonate or slowly to combine the gases, by using different powers of battery, by interposing resisting wires, or by manipulation alone, —a practised hand being able by changing the intervals of contact to combine or detonate the gas at will. My general practice has been to produce a gentle heat in the wire until the gases con­tract, and then gradually to increase the heat until a full ignition takes place, by which means all the objects of the eudiometer of Volta are fulfilled, without detona­tion, without dependence on the fickle electric spark, and without thick tubes, any danger of explosion, or of the gases being projected from the eudiometer. I have commenced with a description of this eudiometer, as it has been indirectly the means of my undertaking the experiments detailed in this lecture; and as its very great convenience has never been generally understood, I think that in strongly re­commending it, I shall be of service to chemists.

scholarly journals Bakerian Lecture—On certain phenomena of voltaic ignition, and on the decomposition of water into its constituent gases by heat

1851 ◽  
Vol 5 ◽  
pp. 657-659
Keyword(s):  
Carbonic Acid ◽  
Glass Tube ◽  
Platinum Wire ◽  
Philosophical Magazine ◽  
Decomposition Of Water

The author refers to an eudiometer, an account of which was published by him in the ‘Philosophical Magazine’ for 1840, formed of a glass tube, into the closed extremity of which a loop of plati­num wire was sealed. The gases to be analysed were mixed in this tube with a given volume of oxygen and hydrogen, and detonated or slowly combined by the voltaic ignition of the platinum wire. He was thence led to try a further set of experiments on the analysis, by this instrument, of such gases and vapours as are decomposable by heat; the process being capable of much greater exactness than the received one of passing them through ignited tubes. The re­sults of the analyses of several gases by this means are given in the paper. When carbonic acid and hydrogen are mixed in equal volumes and exposed to the ignited wire, the hydrogen abstracts oxygen from the carbonic acid, and leaves carbonic oxide. Con­versely, when carbonic oxide is exposed over water to the ignited wire, it abstracts oxygen from the aqueous vapour, and forms car­bonic acid. It thus appeared, that provided there were bodies present capable of absorbing by affinity the elements of water, ignited platinum would either compose or decompose water. The author was thence led to hope that he might by ignited platinum decompose water into its constituents, without absorption by other bodies, and thus pro­duce converse effects to those already known. In this he ultimately succeeded by various methods, in some of which the ignition was produced by electrical means; in others by ordinary calorific pro­cesses, such as the oxyhydrogen blowpipe, &c.

scholarly journals XVI. On the influence of the gulf-stream on the winters of the British Islands. In a letter from Professor Hennessy to Major-General Sabine, V. P. and Treas. R. S. Communicated by Major-General Sabine

1859 ◽  
Vol 9 ◽  
pp. 324-328
Keyword(s):  
Great Britain ◽  
Gulf Stream ◽  
British Isles ◽  
Directed Attention ◽  
Philosophical Magazine ◽  
Mean Temperature ◽  
The Difference ◽  
Thermal Influence ◽  
Major General

My dear Sir,—In your work on 'Pendulum Experiments,’ and subsequently in a paper printed in the ‘Philosophical Magazine’ for April 1846, you have directed attention to the influence of the Gulf-stream on the winters of the British Islands. You have been led to attribute the remarkably mild winters which we sometimes experience, to an abnormal extension of the warm waters of that stream towards our latitudes. In this view I entirely concur, and beg to submit the following additional proof of its correctness. An abnormal extension of the Gulf-stream in the direction of the British Isles necessarily implies that the waters bathing our coasts acquire a temperature which exceeds their mean temperature for the season of the year at which the extension takes place. The temperature of the air over the sea, and finally of the air over the islands, becomes sensibly increased. The entire temperature at any point will thus depend chiefly on what it gains from sunshine, and from the warm sea-air, and on what it loses by radiation. If the excess of what it gains from sunshine over its losses by radiation be considerable compared to its gain from the influence of the sea, the temperature will depend principally on the latitude. If, on the contrary, the thermal influence of the sea be very considerable, places at different latitudes may possess nearly equal temperatures. It follows that during cold winters we should expect a greater difference between the temperatures of the southern coasts of Great Britain and Ireland, and the remainder of their coasts, than during mild winters. It also follows, that during warm winters the difference of temperature between stations situated on coast and inland stations having nearly the same latitude, should be greater than during cold winters.

scholarly journals Design of Large Connectors of Overhead Power Lines

2018 ◽  
Vol 61 (5) ◽  
pp. 432-439 ◽  
Author(s):  
M. A. Korotkevich ◽  
N. V. Prokofieva
Keyword(s):  
Power Transmission ◽  
Power Lines ◽  
Traditional Theory ◽  
Engineering Structures ◽  
Cross Sectional ◽  
Flexible Filament ◽  
Nominal Voltage ◽  
The Wire ◽  
The Difference ◽  
Overhead Power Lines

It is found that the voltage at the lowest points of the wire or cable sag and at the points of their suspension on the pillars in the same span, determined in accordance with the properties of a perfectly flexible filament (similar to which the wires and cables are located in the span), differ slightly, and taking the difference of the mentioned values into account is only of methodologycal importance. The article presents the results of the calculation of wire and cable sag of large spans of power transmission line of 500 m or more length using both the traditional theory of the catenary line and the theory of equal resistance, when the cross-sectional area of a wire or cable, proportional to their tension, is considered variable in the span length, which provides the same probability of breaking them at any point of the span. When calculating the wires and cables in normal and emergency conditions, the largest sags are determined, which take place either at a higher ambient temperature or at a load of the wire with ice. The wire must be mounted in such a way as to ensure the normalized permissible dimensions to crossed engineering structures, water barriers or land, that are determined depending on the nominal voltage of the line. It is noted that the values of the wire and cable sags determined using the theory of the catenary line for the transition spans are less (although slightly) as compared to the data obtained on the basis of the theory of the equal resistance circuit. This must be taken into account in the design process.

A bidirectional respiratory flowmeter using the hot-wire principle

1975 ◽  
Vol 38 (2) ◽  
pp. 360-365 ◽  
Author(s):  
I. Yoshiya ◽  
T. Nakajima ◽  
I. Nagai ◽  
S. Jitsukawa
Keyword(s):  
Temperature Difference ◽  
Flow Measurement ◽  
Flow Direction ◽  
Differential Amplifier ◽  
Platinum Wire ◽  
Hot Wire ◽  
Quiet Breathing ◽  
Switching Times ◽  
Respiratory Flow ◽  
The Difference

We have devised a bidirectional respiratory flowmeter using the hot-wire principle. The flow-direction sensor consists of a pair of tungsten wires strung parallel to the platinum hot-wire one on each side of the platinum wire. When the gas stream passes through the transducer, the upstream wire is cooled and the downstream wire is heated by the gas stream producing a temperature difference between the two tungsten wires. The difference in resistance thus produced between them is detected and amplified by a differential amplifier whose output serves as a triggering signal of flow inversion. The switching times of the flow inversion of the present instrument are 3 ms during panting and 10 ms during quiet breathing, when the distances from the platinum wire to the tungsten wires are 1.6 mm. Artifacts produced by the delay in switching are practically negligible. The flowmeter can be adapted for many kinds of respiratory flow measurement, except under the condition when inflammable gases are used.

scholarly journals Mitigation of seal-induced damage in salmon and whitefish trapnet fisheries by modification of the fish bag

2004 ◽  
Vol 61 (7) ◽  
pp. 1195-1200 ◽  
Author(s):  
Esa Lehtonen ◽  
Petri Suuronen
Keyword(s):  
Halichoerus Grypus ◽  
Coregonus Lavaretus ◽  
Wire Grid ◽  
The Past ◽  
Steel Wires ◽  
Bag Experiments ◽  
The Wire ◽  
The Difference ◽  
The Baltic ◽  
The Gulf Of Finland

Abstract During the past decade, seal-induced gear and catch damage has increased dramatically in the Baltic Sea. The problems are most severe in the coastal trapnet fisheries for salmon (Salmo salar) and whitefish (Coregonus lavaretus), where grey seals (Halichoerus grypus) in particular frequently visit the traps. There is an acute need for gear modifications and other solutions that can prevent seals from entering the fish bag of the traps. Modifications that have been tested in Finland include a wire grid installed in the funnel of the trap and a fish bag made of extra-strong netting material. In comparative fishing experiments conducted in 2001 in the Gulf of Finland the grid was made of 2-mm steel wires with 175-mm spacing. The average undamaged salmon catch per haul in the fish bag of modified trapnets was significantly higher (70%) than that of traditional traps (Mann–Whitney, p < 0.01). In the whitefish experiments, the average undamaged catch of whitefish per haul was 16% higher in modified trapnets than in traditional traps, but the difference was not significant (Mann–Whitney, p > 0.05). These results indicate that the wire grid did not prevent fish from swimming into the fish bag. Experiments also suggest that the wire grid and the extra-strong netting prevented seals from entering the bag. However, on some occasions seals were able to tear the fish through the netting. Underwater observations confirmed that the wire grid kept adult seals outside the bag while salmon and whitefish could be seen entering through the grid into the bag.

Mechanisms of gas exchange with different gases during constant-flow ventilation

1990 ◽  
Vol 68 (1) ◽  
pp. 88-93 ◽  
Author(s):  
F. J. Chen ◽  
A. S. Menon ◽  
S. V. Lichtenstein ◽  
N. Zamel ◽  
A. S. Slutsky
Keyword(s):  
Gas Exchange ◽  
Physical Properties ◽  
Flow Rate ◽  
Constant Flow ◽  
Catheter Position ◽  
Arterial Pco2 ◽  
The Mean ◽  
The Difference ◽  
The Individual ◽  
Different Gases

To investigate the mechanisms responsible for the difference in gas exchange during constant-flow ventilation (CFV) when using gases with different physical properties, we used mixtures of 70% N2-30% O2 (N2-O2) and 70% He-30% O2 (He-O2) as the insufflating gases in 12 dogs. All dogs but one had higher arterial PCO2 (PaCO2) with He-O2 compared with N2-O2. At a flow of 0.37 +/- 0.12 l/s, the mean PaCO2's with N2-O2 and He-O2 were 41.3 +/- 13.9 and 53.7 +/- 20.3 Torr, respectively (P less than 0.01); at a flow rate of 0.84 +/- 0.17 l/s, the mean PaCO2's were 29.1 +/- 11.3 and 35.3 +/- 13.6 Torr, respectively (P less than 0.01). The chest was then opened to alter the apposition between heart and the lungs, thereby reducing the extent of cardiogenic oscillations by 58.4 +/- 18.4%. This intervention did not significantly alter the difference in PaCO2 between N2-O2 and He-O2 from that observed in the intact animals, although the individual PaCO2 values for each gas mixture did increase. When the PaCO2 was plotted against stagnation pressure (rho V2), the difference in PaCO2 between N2-O2 and He-O2 was nearly abolished in both the closed- and open-chest animals. These findings suggest that the different PaCO2's obtained by insufflating gases with different physical properties at a fixed flow rate, catheter position, and lung volume result mainly from a difference in the properties of the jet.

scholarly journals ON INTERACTION OF A LIQUID FILM WITH AN OBSTACLE

2002 ◽  
Vol 7 (2) ◽  
pp. 327-342 ◽  
Author(s):  
A. Zemitis
Keyword(s):  
Liquid Film ◽  
Mathematical Models ◽  
Numerical Experiments ◽  
Impinging Jets ◽  
Numerical Results ◽  
Qualitative Behavior ◽  
Different Shapes ◽  
The Wire ◽  
The Difference

In this paper are discussed mathematical models for the liquid film generated by impinging jets. These models describe only the film shape under special assumptions about processes. Attention is stressed on the interaction of the liquid film with some obstacle. The idea is to generalize existing models and to investigate qualitative behavior of liquid film using numerical experiments. G.I. Taylor [Proc. R. Soc. London Ser. A 253, 313 (1959)] found that the liquid film generated by impinging jets is very sensitive to properties of the wire which was used as an obstacle. The aim of this presentation is to propose a modification of the Taylor's model, which allows to simulate the film shape in cases when the angle between jets is different from 180°. Numerical results obtained by discussed models give two different shapes of the liquid film similar as in Taylors experiments. These two shapes depend on the regime: either droplets are produced close to the obstacle or not. The difference between two regimes becomes larger if the angle between jets decreases. Existence of such two regimes can be very essential for some applications of impinging jets, if the generated liquid film can have a contact with obstacles.

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