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calorimeter

calorimeter

calorimeter Sentence Examples

  • A calorimeter is any piece of apparatus in which heat is measured.

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  • Lavoisier he made an important series of experiments on specific heat (1782-1784), in the course of which the "ice calorimeter" was invented; and they contributed jointly to the Memoirs of the Academy (1781) a paper on the development of electricity by evaporation.

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  • The calorimeter tube was calibrated by a thread of mercury weighing 19 milligrams, which occupied eighty-five divisions.

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  • The calorimeter used for solutions is usually cylindrical, and made of glass or a metal which is not, attacked by the reacting substances.

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  • It is better to use a fairly large calorimeter to diminish the rate of cooling and the uncertainty of the correction for the water equivalent.

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  • The present writer has found that very good results may be obtained by enclosing the calorimeter in a vacuum jacket (as illustrated in fig.

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  • The same type of calorimeter is used in determining the heat of solution of a solid or liquid in water.

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  • In the older type the combustion chamber (of metal or glass) is sunk in the calorimeter proper, tubes being provided for the entrance and exit of the gaseous substances involved in the action.

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  • It can be minimized by making the mixing as rapid as possible, and by using a large calorimeter, so that the excess of temperature is always small.

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  • The same type of calorimeter is used in determining the heat of solution of a solid or liquid in water.

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  • To test this two vessels similar to that used in the last experiment were placed in the same calorimeter and connected by a tube with a stop-cock.

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  • On repeating the experiment when the two vessels were placed in different calorimeters, it was found that heat was absorbed by the vessel containing the compressed air, while an equal quantity of heat was produced in the calorimeter containing the exhausted vessel.

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  • When the solutions employed are dilute, no water is placed in the calorimeter, the temperature-change of the solutions themselves being used to estimate the thermal effect brought about by mixing them.

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  • It is of course in such a case necessary to know the specific heat of the liquid in the calorimeter.

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  • These tubes are generally in the form of worms immersed in the water of the calorimeter.

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  • The steel combustion chamber is of about 250 c.c. capacity, and is wholly immersed in the calorimeter.

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  • For ordinary combustions compressed oxygen is used, so that the combustible substance burns almost instantaneously, the action being induced by means of some electrical device which can be controlled from without the calorimeter.

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  • The accuracy of heats of combustion determined in the closed calorimeter is in favourable cases about one-half per cent.

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  • This test was applied by Joule in the well-known experiment in which he allowed a gas to expand from one vessel to another in a calorimeter without doing external work.

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  • Under this condition the increase of intrinsic energy would be equal to the heat absorbed, and would be indicated by fall of temperature of the calorimeter.

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  • But owing to the large thermal capacity of his calorimeter, the test, though sufficient for his immediate purpose, was not delicate enough to detect and measure the small deviations which actually exist.

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  • If the heat of solution be measured in a calorimeter, no work is done, so that, if we call this calorimetric heat of solution L, the two quantities are connected by the relation L = X+P(v - v).

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  • If l is the heat of dilution per unit change of volume in a calorimeter where all the energy goes to heat, the change in internal energy U is measured by ldv.

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  • between the heater and the calorimeter.

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  • The gradient near the entrance to the calorimeter was deduced from observations with five thermometers at suitable intervals along the bar.

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  • The heat-flow through the central column amounted to about 7.5 calories in 54 seconds, and was measured by continuing the tube through the iron plate into the bulb of a Bunsen ice calorimeter, and observing with a chronometer to a fifth of a second the time taken by the mercury to contract through a given number of divisions.

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  • The chief uncertainty of this method is the area from which the heat is collected, which probably exceeds that of the central column, owing to the disturbance of the linear flow by the projecting bulb of the calorimeter.

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  • The two carried out some of the earliest thermochemical investigations, devised apparatus for measuring linear and cubical expansions, and employed a modification of Joseph Black's ice calorimeter in a series of determinations of specific heats.

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  • The Method of Mixture consists in imparting the quantity of heat to be measured to a known mass of water, or some other standard substance, contained in a vessel or calorimeter of known thermal capacity, and in observing the rise of temperature produced, from which data the quantity of heat may be found as explained in all elementary text-books.

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  • Some heat is generally lost in transferring the heated body to the calorimeter; this loss may be minimized by performing the transference rapidly, but it cannot be accurately calculated or eliminated.

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  • Some heat is lost when the calorimeter is raised above the temperature of its enclosure, and before the final temperature is reached.

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  • The coefficient of heating of a calorimeter when it is below the temperature of its surroundings is seldom, if ever, the same as the coefficient of cooling at the higher temperature, since the convection currents, which do most of the heating or cooling, are rarely symmetrical in the two cases, and moreover, the duration of the two stages is seldom the same.

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  • In any case, it is desirable to diminish the loss of heat as much as possible by polishing the exterior of the calorimeter to diminish radiation, and by suspending it by non-conducting supports, inside a polished case, to protect it from draughts.

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  • The method of lagging the calorimeter with cotton-wool or other non-conductors, which is often recommended, diminishes the loss of heat considerably, but renders it very uncertain and variable, and should never be used in work of precision.

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  • The bad conductors take so long to reach a steady state that the rate of loss of heat at any moment depends on the past history more than on the temperature of the calorimeter at the moment.

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  • The least trace of damp in the lagging, or of moisture condensed on the surface of the calorimeter, may produce serious loss of heat by evaporation.

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  • This is another objection to Rumford's method of cooling the calorimeter below the surrounding temperature before starting.

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  • It is best to make this correction as small as possible by using a large calorimeter, so that the mass of water is large in proportion to that of metal.

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  • temperature is added to the calorimeter, immediately after dropping in the heated substance, at such a rate as to keep the temperature of the calorimeter constant, thus eliminating the corrections for the water equivalent of the calorimeter and the external loss of heat.

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  • The calorimeter is surrounded by an air-jacket connected to a petroleum gauge which indicates any small change of temperature in the calorimeter, and enables the manipulator to adjust the supply of cold water to compensate it.

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  • H is an electric heater for raising the body to a suitable temperature, which can swing into place directly over the calorimeter.

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  • W is a conical can containing water cooled by ice I nearly to o°, which is swung over the calorimeter as soon as the hot body has been introduced and the heater removed.

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  • 2 illustrates a recent type of gas calorimeter devised by C. V.

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  • A common example of this method is the determination of the specific heat of a liquid by filling a small calorimeter with the liquid, raising it to a convenient temperature, and then setting it to cool in an enclosure at a steady temperature, and observing the time taken to fall through a given range when the conditions have become fairly steady.

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  • The same calorimeter is afterwards filled with a known liquid, such as water, and the time of cooling is observed through the same range of temperature, in the same enclosure, under the same conditions.

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  • The ratio of the times of cooling is equal to the ratio of the thermal capacities of the calorimeter and its contents in the two cases.

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  • As the method is usually practised, the calorimeter is made very small, and the surface is highly polished to diminish radiation.

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  • For accurate work it is essential that the liquid in the calorimeter should be continuously stirred, and also in the enclosure, the lid of which must be waterjacketed, and kept at the same steady temperature as the sides.

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  • This difficulty was overcome by the invention of the Bunsen calorimeter, in which the quantity of ice melted is measured by observing the diminution of volume, but the successful employment of this instrument requires considerable skill in manipulation.

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  • One of the chief difficulties in the practical use of the Bunsen calorimeter is the continued and often irregular movement of the mercury column due to slight differences of temperature, or pressure between the ice in the calorimeter and the ice bath in which it is immersed.

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  • 24, p. 214) showed that these effects could be very greatly reduced by surrounding the calorimeter with an outer tube, so that the ice inside was separated from the ice outside by an air space which greatly reduces the free passage of heat.

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  • If the inner bulb is filled with mercury instead of water and ice, the same arrangement answers admirably as a Favre and Silbermann calorimeter, for measuring small quantities of heat by the expansion of FIG.

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  • If such variations of density exist, they may introduce some uncertainty in the absolute values of results obtained with the ice calorimeter, and may account for some of the discrepancies above enumerated.

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  • Joly in the construction of his steam calorimeter, a full description of which will be found in text-books.

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  • 4) the paddles were revolved by hand at such a speed as to produce a constant torque on the calorimeter h, which was supported on a float w in a vessel of water v, but was kept at rest by the couple due to a pair of equal weights k suspended from fine strings passing round the circumference of a horizontal wheel attached to the calorimeter.

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  • Each experiment lasted about forty minutes, and the rise of temperature produced was nearly 3° C. The calorimeter contained about 5 kilogrammes of water, so that the rate of heat-supply was about 6 calories per second.

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  • P. 75, 1880) Repeated The Experiment, Employing The Same Method, But Using A Larger Calorimeter (About 8400 Grammes) And A Petroleum Motor, So As To Obtain A Greater Rate Of Heating (About 84 Calories Per Second), And To Reduce The Importance Of The Uncertain Correction For External Loss Of Heat.

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  • The Calorimeter Was Suspended By A Steel Wire, The Torsion Of Which Made The Equilibrium Stable.

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  • The Power Was Transmitted To The Paddles By Bevel Wheels F, G, Rotating A Spindle Passing Through A Stuffing Box In The Bottom Of The Calorimeter.

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  • The Water Equivalent Of The Calorimeter Was About 85 Grammes, And Was Determined By Varying The Quantity Of Water From 140 To 260 Or 280 Grammes, So That The Final Results Depended On A Difference In The Weight Of Water Of 120 To 140 Grammes.

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  • The Current Through A Platinoid Resistance Of About 31 Ohms In A Calorimeter Containing 1500 Grammes Of Water Was Regulated So That The Potential Difference On Its Terminals Was Equal To That Of Twenty Board Of Trade Clark Cells In Series.

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  • The Water Equivalent Of The Calorimeter Is Immaterial, Since There Is No Appreciable Change Of Temperature.

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  • The Rapid Rise From 25° To 75° May Be Due To Radiation Error From The Hot Water Supply, And The Subsequent Fall Of The Curve To The Inevitable Loss Of Heat By Evaporation Of The Boiling Water On Its Way To The Calorimeter.

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  • The Direct Determination Of The Specific Heat At Constant Volume Is Extremely Difficult, But Has Been Successfully Attempted By Joly With His Steam Calorimeter, In The Case Of Air And C02.

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  • The method commonly adopted in measuring the latent heat of a vapour is to condense the vapour at saturation-pressure in a calorimeter.

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  • The quantity of heat so measured is the total heat of the vapour reckoned from the final temperature of the calorimeter, and the heat of the liquid h must be subtracted from the total heat measured to find the latent heat of the vapour at the given temperature.

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  • Another method, which is suitable for volatile liquids or low temperatures, is to allow the liquid to evaporate in a calorimeter, and to measure the quantity of heat required for the evaporation of the liquid at the temperature of the calorimeter and at saturation-pressure.

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  • The specific heat of steam was determined shortly afterwards by Regnault (Comptes Rendus, 36, p. 676) by condensing superheated steam at two different temperatures (about 125° and 225° C.) successively in the same calorimeter at atmospheric pressure, and taking the difference of the total heats observed.

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  • The ideal method of determining by direct experiment the relation between the total heat and the specific heat of a vapour is that of Joule and Thomson, which is more commonly known in connexion with steam as the method of the throttling calorimeter.

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  • The simplest method of measuring the specific heat appears to be that of supplying heat electrically to a steady current of vapour in a vacuum-jacket calorimeter, and observing the rise of temperature produced.

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  • - Throttling Calorimeter Method.

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  • Callendar's experiments on the cooling effect for steam by the throttling calorimeter method gave n =3-33 and c =26.3 c.c. at 100° C. Grindley's experiments gave nearly the same average value of Q over his experimental range, but a rather larger value for n, namely, 3.8.

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  • The original intention was to push the experiments to a pressure equivalent to thirty atmospheres, but owing to the signs of failure exhibited by the boiler the limit actually reached was twenty-four atmospheres, at which pressure the thermometers indicated a temperature of about 224 0 C. In his last paper, published posthumously in 1838, Dulong gave an account of experiments made to determine the heat disengaged in the combination of various simple and compound bodies, together with a description of the calorimeter he employed.

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  • He enclosed various metallic junctions in a Bunsen ice calorimeter, and observed the evolution of heat per hour with a current of about 1.6 amperes in either direction.

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  • effect was calculated by multiplying this difference of temperature by the thermal capacity of either calorimeter, and dividing by the current, by the number of seconds in twenty minutes, and by twice the difference of temperature (about 20°) between the ends a and b of either calorimeter.

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  • The electrical connections to the calorimeter are actually made to thin metallic members in the liquid argon (" electrodes " ).

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  • The DSC 204 Phoenix differential scanning calorimeter can be equipped with an automatic sample changer for up to 64 samples.

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  • calorimeter used to measure it.

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  • In 1911 he constructed a special calorimeter that measured specific heats at very low temperatures.

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  • calorimeter built as part of this project has been improved and is being used for measuring motor losses to a high accuracy.

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  • Next on its outward journey the particle passes through a detector called the " electromagnetic calorimeter " .

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  • The UK Contribution to BaBar The UK groups have constructed the forward endcap calorimeter and the signal-processing and triggering electronics for the whole calorimeter.

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  • Chemicals can be tested in a simple calorimeter to measure the temperature rise.

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  • The entire electromagnetic calorimeter at TESLA comprises a cylinder of length 5.5m, internal radius 1.9m, and annular thickness of 20cm.

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  • Electromagnetic calorimeter (EMC) A high quality electromagnetic calorimeter is an essential feature of B A B AR.

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  • calorimeter clusters etc. * Event Query Tag Data (tag ).

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  • calorimeter cells.

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  • calorimeter trigger expert wishes to get immediate feedback that the clusters which are being reconstructed are consistent with expectations.

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  • calorimeter energy calibration using Virtual Compton Scattering (VCS) events.

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  • calorimeter system.

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  • The hadronic calorimeter measures the energy carried by hadrons entering each of its segments (see figure ).

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  • hadron calorimeter: This device measures the total energy of hadrons.

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  • It is measured by the complete oxidation of the food in a bomb calorimeter.

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  • The primary standard used for this service is a graphite calorimeter and so absorbed dose calibrations must be converted from graphite to water.

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  • The tests range from small scale charring tests (cone calorimeter) to large scale furnace tests.

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  • electromagnetic calorimeter.

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  • Hadron calorimeter: This device measures the total energy of hadron calorimeter: This device measures the total energy of hadrons.

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  • A metal vessel was placed in a calorimeter and air forced into it, the amount of energy expended in compressing the air being measured.

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  • In the next experiment the air was compressed as before, and then allowed to escape through a long lead tube immersed in the water of a calorimeter, and finally collected in a bell jar.

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  • To test this two vessels similar to that used in the last experiment were placed in the same calorimeter and connected by a tube with a stop-cock.

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  • On repeating the experiment when the two vessels were placed in different calorimeters, it was found that heat was absorbed by the vessel containing the compressed air, while an equal quantity of heat was produced in the calorimeter containing the exhausted vessel.

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  • When the solutions employed are dilute, no water is placed in the calorimeter, the temperature-change of the solutions themselves being used to estimate the thermal effect brought about by mixing them.

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  • It is of course in such a case necessary to know the specific heat of the liquid in the calorimeter.

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  • The calorimeter used for solutions is usually cylindrical, and made of glass or a metal which is not, attacked by the reacting substances.

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  • In the older type the combustion chamber (of metal or glass) is sunk in the calorimeter proper, tubes being provided for the entrance and exit of the gaseous substances involved in the action.

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  • These tubes are generally in the form of worms immersed in the water of the calorimeter.

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  • The steel combustion chamber is of about 250 c.c. capacity, and is wholly immersed in the calorimeter.

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  • For ordinary combustions compressed oxygen is used, so that the combustible substance burns almost instantaneously, the action being induced by means of some electrical device which can be controlled from without the calorimeter.

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  • The accuracy of heats of combustion determined in the closed calorimeter is in favourable cases about one-half per cent.

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  • Lavoisier he made an important series of experiments on specific heat (1782-1784), in the course of which the "ice calorimeter" was invented; and they contributed jointly to the Memoirs of the Academy (1781) a paper on the development of electricity by evaporation.

    0
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  • This test was applied by Joule in the well-known experiment in which he allowed a gas to expand from one vessel to another in a calorimeter without doing external work.

    0
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  • Under this condition the increase of intrinsic energy would be equal to the heat absorbed, and would be indicated by fall of temperature of the calorimeter.

    0
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  • But owing to the large thermal capacity of his calorimeter, the test, though sufficient for his immediate purpose, was not delicate enough to detect and measure the small deviations which actually exist.

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  • If the heat of solution be measured in a calorimeter, no work is done, so that, if we call this calorimetric heat of solution L, the two quantities are connected by the relation L = X+P(v - v).

    0
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  • If l is the heat of dilution per unit change of volume in a calorimeter where all the energy goes to heat, the change in internal energy U is measured by ldv.

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  • between the heater and the calorimeter.

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  • The gradient near the entrance to the calorimeter was deduced from observations with five thermometers at suitable intervals along the bar.

    0
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  • The heat-flow through the central column amounted to about 7.5 calories in 54 seconds, and was measured by continuing the tube through the iron plate into the bulb of a Bunsen ice calorimeter, and observing with a chronometer to a fifth of a second the time taken by the mercury to contract through a given number of divisions.

    0
    0
  • The calorimeter tube was calibrated by a thread of mercury weighing 19 milligrams, which occupied eighty-five divisions.

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  • The chief uncertainty of this method is the area from which the heat is collected, which probably exceeds that of the central column, owing to the disturbance of the linear flow by the projecting bulb of the calorimeter.

    0
    0
  • The two carried out some of the earliest thermochemical investigations, devised apparatus for measuring linear and cubical expansions, and employed a modification of Joseph Black's ice calorimeter in a series of determinations of specific heats.

    0
    0
  • A calorimeter is any piece of apparatus in which heat is measured.

    0
    0
  • The Method of Mixture consists in imparting the quantity of heat to be measured to a known mass of water, or some other standard substance, contained in a vessel or calorimeter of known thermal capacity, and in observing the rise of temperature produced, from which data the quantity of heat may be found as explained in all elementary text-books.

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  • Some heat is generally lost in transferring the heated body to the calorimeter; this loss may be minimized by performing the transference rapidly, but it cannot be accurately calculated or eliminated.

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  • Some heat is lost when the calorimeter is raised above the temperature of its enclosure, and before the final temperature is reached.

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  • It can be minimized by making the mixing as rapid as possible, and by using a large calorimeter, so that the excess of temperature is always small.

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  • Rumford proposed to eliminate this correction by starting with the initial temperature of the calorimeter as much below that of its enclosure as the final temperature was expected to be above the same limit.

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  • The coefficient of heating of a calorimeter when it is below the temperature of its surroundings is seldom, if ever, the same as the coefficient of cooling at the higher temperature, since the convection currents, which do most of the heating or cooling, are rarely symmetrical in the two cases, and moreover, the duration of the two stages is seldom the same.

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  • In any case, it is desirable to diminish the loss of heat as much as possible by polishing the exterior of the calorimeter to diminish radiation, and by suspending it by non-conducting supports, inside a polished case, to protect it from draughts.

    0
    0
  • The method of lagging the calorimeter with cotton-wool or other non-conductors, which is often recommended, diminishes the loss of heat considerably, but renders it very uncertain and variable, and should never be used in work of precision.

    0
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  • The bad conductors take so long to reach a steady state that the rate of loss of heat at any moment depends on the past history more than on the temperature of the calorimeter at the moment.

    0
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  • The least trace of damp in the lagging, or of moisture condensed on the surface of the calorimeter, may produce serious loss of heat by evaporation.

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  • This is another objection to Rumford's method of cooling the calorimeter below the surrounding temperature before starting.

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  • Among minor difficulties of the method may be mentioned the uncertainty of the thermal capacity of the calorimeter and stirrer, and of the immersed portion of the thermometer.

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  • It is best to make this correction as small as possible by using a large calorimeter, so that the mass of water is large in proportion to that of metal.

    0
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  • temperature is added to the calorimeter, immediately after dropping in the heated substance, at such a rate as to keep the temperature of the calorimeter constant, thus eliminating the corrections for the water equivalent of the calorimeter and the external loss of heat.

    0
    0
  • The calorimeter is surrounded by an air-jacket connected to a petroleum gauge which indicates any small change of temperature in the calorimeter, and enables the manipulator to adjust the supply of cold water to compensate it.

    0
    0
  • H is an electric heater for raising the body to a suitable temperature, which can swing into place directly over the calorimeter.

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  • W is a conical can containing water cooled by ice I nearly to o°, which is swung over the calorimeter as soon as the hot body has been introduced and the heater removed.

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  • The method is interesting, but the manipulations and observations involved are more troublesome than with the ordinary type of calorimeter, and it may be doubted whether any advantage is gained in accuracy.

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  • 2 illustrates a recent type of gas calorimeter devised by C. V.

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  • A continuous flow calorimeter has been used by the writer for measuring quantities of heat conveyed by conduction (see Conduction Of Heat), and also for determining the variation of the specific heat of water.

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  • A common example of this method is the determination of the specific heat of a liquid by filling a small calorimeter with the liquid, raising it to a convenient temperature, and then setting it to cool in an enclosure at a steady temperature, and observing the time taken to fall through a given range when the conditions have become fairly steady.

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  • The same calorimeter is afterwards filled with a known liquid, such as water, and the time of cooling is observed through the same range of temperature, in the same enclosure, under the same conditions.

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  • The ratio of the times of cooling is equal to the ratio of the thermal capacities of the calorimeter and its contents in the two cases.

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  • As the method is usually practised, the calorimeter is made very small, and the surface is highly polished to diminish radiation.

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  • It is better to use a fairly large calorimeter to diminish the rate of cooling and the uncertainty of the correction for the water equivalent.

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  • The surface of the calorimeter and the enclosure should be permanently blackened so as to increase the loss of heat by radiation as much as possible, as compared with the losses by convection and conduction, which are less regular.

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  • For accurate work it is essential that the liquid in the calorimeter should be continuously stirred, and also in the enclosure, the lid of which must be waterjacketed, and kept at the same steady temperature as the sides.

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  • This difficulty was overcome by the invention of the Bunsen calorimeter, in which the quantity of ice melted is measured by observing the diminution of volume, but the successful employment of this instrument requires considerable skill in manipulation.

    0
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  • One of the chief difficulties in the practical use of the Bunsen calorimeter is the continued and often irregular movement of the mercury column due to slight differences of temperature, or pressure between the ice in the calorimeter and the ice bath in which it is immersed.

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  • 24, p. 214) showed that these effects could be very greatly reduced by surrounding the calorimeter with an outer tube, so that the ice inside was separated from the ice outside by an air space which greatly reduces the free passage of heat.

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  • The present writer has found that very good results may be obtained by enclosing the calorimeter in a vacuum jacket (as illustrated in fig.

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  • If the inner bulb is filled with mercury instead of water and ice, the same arrangement answers admirably as a Favre and Silbermann calorimeter, for measuring small quantities of heat by the expansion of FIG.

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  • If such variations of density exist, they may introduce some uncertainty in the absolute values of results obtained with the ice calorimeter, and may account for some of the discrepancies above enumerated.

    0
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  • Joly in the construction of his steam calorimeter, a full description of which will be found in text-books.

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  • 4) the paddles were revolved by hand at such a speed as to produce a constant torque on the calorimeter h, which was supported on a float w in a vessel of water v, but was kept at rest by the couple due to a pair of equal weights k suspended from fine strings passing round the circumference of a horizontal wheel attached to the calorimeter.

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  • Each experiment lasted about forty minutes, and the rise of temperature produced was nearly 3° C. The calorimeter contained about 5 kilogrammes of water, so that the rate of heat-supply was about 6 calories per second.

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  • P. 75, 1880) Repeated The Experiment, Employing The Same Method, But Using A Larger Calorimeter (About 8400 Grammes) And A Petroleum Motor, So As To Obtain A Greater Rate Of Heating (About 84 Calories Per Second), And To Reduce The Importance Of The Uncertain Correction For External Loss Of Heat.

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  • The Calorimeter Was Suspended By A Steel Wire, The Torsion Of Which Made The Equilibrium Stable.

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  • The Power Was Transmitted To The Paddles By Bevel Wheels F, G, Rotating A Spindle Passing Through A Stuffing Box In The Bottom Of The Calorimeter.

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  • Trans.,1897, P. 381) Determined The Mechanical Equivalent Of The Mean Thermal Unit Between O° And Ioo° C., On A Very Large Scale, With A Froude Reynolds Hydraulic Brake And A Steam Engine Of Ioo H.P. This Brake Is Practically A Joule Calorimeter, Ingeniously Designed To Churn The Water In Such A Manner As To Develop The Greatest Possible Resistance.

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  • The Resistance R Could Be Deduced From A Knowledge Of The Temperature Of The Calorimeter And The Coefficient Of The Wire.

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  • The Water Equivalent Of The Calorimeter Was About 85 Grammes, And Was Determined By Varying The Quantity Of Water From 140 To 260 Or 280 Grammes, So That The Final Results Depended On A Difference In The Weight Of Water Of 120 To 140 Grammes.

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  • The Calorimeter C, Fig.

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  • The Current Through A Platinoid Resistance Of About 31 Ohms In A Calorimeter Containing 1500 Grammes Of Water Was Regulated So That The Potential Difference On Its Terminals Was Equal To That Of Twenty Board Of Trade Clark Cells In Series.

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  • The Water Equivalent Of The Calorimeter Is Immaterial, Since There Is No Appreciable Change Of Temperature.

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  • The Rapid Rise From 25° To 75° May Be Due To Radiation Error From The Hot Water Supply, And The Subsequent Fall Of The Curve To The Inevitable Loss Of Heat By Evaporation Of The Boiling Water On Its Way To The Calorimeter.

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  • The Direct Determination Of The Specific Heat At Constant Volume Is Extremely Difficult, But Has Been Successfully Attempted By Joly With His Steam Calorimeter, In The Case Of Air And C02.

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  • The method commonly adopted in measuring the latent heat of a vapour is to condense the vapour at saturation-pressure in a calorimeter.

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  • The quantity of heat so measured is the total heat of the vapour reckoned from the final temperature of the calorimeter, and the heat of the liquid h must be subtracted from the total heat measured to find the latent heat of the vapour at the given temperature.

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  • Another method, which is suitable for volatile liquids or low temperatures, is to allow the liquid to evaporate in a calorimeter, and to measure the quantity of heat required for the evaporation of the liquid at the temperature of the calorimeter and at saturation-pressure.

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  • The specific heat of steam was determined shortly afterwards by Regnault (Comptes Rendus, 36, p. 676) by condensing superheated steam at two different temperatures (about 125° and 225° C.) successively in the same calorimeter at atmospheric pressure, and taking the difference of the total heats observed.

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  • The ideal method of determining by direct experiment the relation between the total heat and the specific heat of a vapour is that of Joule and Thomson, which is more commonly known in connexion with steam as the method of the throttling calorimeter.

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  • The simplest method of measuring the specific heat appears to be that of supplying heat electrically to a steady current of vapour in a vacuum-jacket calorimeter, and observing the rise of temperature produced.

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  • - Throttling Calorimeter Method.

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  • Callendar's experiments on the cooling effect for steam by the throttling calorimeter method gave n =3-33 and c =26.3 c.c. at 100° C. Grindley's experiments gave nearly the same average value of Q over his experimental range, but a rather larger value for n, namely, 3.8.

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  • The original intention was to push the experiments to a pressure equivalent to thirty atmospheres, but owing to the signs of failure exhibited by the boiler the limit actually reached was twenty-four atmospheres, at which pressure the thermometers indicated a temperature of about 224 0 C. In his last paper, published posthumously in 1838, Dulong gave an account of experiments made to determine the heat disengaged in the combination of various simple and compound bodies, together with a description of the calorimeter he employed.

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  • He enclosed various metallic junctions in a Bunsen ice calorimeter, and observed the evolution of heat per hour with a current of about 1.6 amperes in either direction.

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  • effect was calculated by multiplying this difference of temperature by the thermal capacity of either calorimeter, and dividing by the current, by the number of seconds in twenty minutes, and by twice the difference of temperature (about 20°) between the ends a and b of either calorimeter.

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  • In the next experiment the air was compressed as before, and then allowed to escape through a long lead tube immersed in the water of a calorimeter, and finally collected in a bell jar.

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  • Rumford proposed to eliminate this correction by starting with the initial temperature of the calorimeter as much below that of its enclosure as the final temperature was expected to be above the same limit.

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  • The method is interesting, but the manipulations and observations involved are more troublesome than with the ordinary type of calorimeter, and it may be doubted whether any advantage is gained in accuracy.

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  • The Calorimeter C, Fig.

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  • A metal vessel was placed in a calorimeter and air forced into it, the amount of energy expended in compressing the air being measured.

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  • Among minor difficulties of the method may be mentioned the uncertainty of the thermal capacity of the calorimeter and stirrer, and of the immersed portion of the thermometer.

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  • The surface of the calorimeter and the enclosure should be permanently blackened so as to increase the loss of heat by radiation as much as possible, as compared with the losses by convection and conduction, which are less regular.

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  • The Resistance R Could Be Deduced From A Knowledge Of The Temperature Of The Calorimeter And The Coefficient Of The Wire.

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