Clement-Desormes experiment

The method described in Problem 7.20 is that of Clement-Desormes for determining y, the heat capacity ratio. In an experiment, a gas is confined initially under = 151.2 kPa pressure. The ambient pressure, p2 = 100.8 kPa, and the final pressure after temperature equilibration is pa = 116.3 kPa. Calculate y for this gas. Assume the gas is ideal. 

Faraday reported that a current of steam passed into solutions of salts, acids, sugar, etc., raised the solution to the b.p. (over 100°), but the steam leaving the solution had a temperature of 100° as read by a thermometer. Gay-Lussac 5 said this had been found by Desormes, Clement, and Champy about 1810 but not published. Gay-Lussac thought the steam from a boiling solution had the temperature of the surface of the liquid, but condensed as a film of water on the thermometer bulb, which registered 100° if loss of heat from the thermometer were prevented, this condensation would not occur and the temperature of the vapour would be that of the solution. The question has often been discussed (mostly by industrial chemists), sometimes in favour of Faraday s, sometimes in favour of Gay-Lussac s, finding. Schreber s experiments favoured Faraday s Reissmann found exactly the opposite result. 

As a result of inexact experiments, Creighton and Southern (1803) supposed that the latent heat of steam, 4, was independent of temperature, whilst Watt supposed that the total heat, was independent of temperature. Experiments of Clement and Desormes seemed to confirm Watt s assumption, which was generally adopted by engineers and called JVatt s law. Both laws were shown to be incorrect by the careful experiments of Regnault, who found... 

Faraday in his diary says Ampere, Clement, and Desormes came this morning [23 November 1813] to show Sir H. Davy a new substance, discovered, about two years ago, by M. Courtois, saltpetre manufacturer. The process by which it is obtained is not yet publicly known. It is said to be procured from a very common substance, and in considerable quantities . Very little information would seem to have been given to Davy, who at first (says Faraday) thought it was a compound of chlorine and an unknown body, although the entry for the same day says Davy now thinks it contains no chlorine . On I December, Faraday says, Davy had made many experiments on it with his travelling apparatus M. Clement has lately read a paper on it... in which he says it is procured from the ashes of sea-weeds by lixiviation and treatment with sulphuric acid. He conceives it to be a new supporter of combustion. On 3 December, Davy was working on it in Chevreul s laboratory and on ii December he concluded that as yet it must be considered as a simple body . 

Guyton then reported that the gaz oxide de carbone is oxidised in the cold by chlorine in presence of water, forming carbonic acid. Desormes and Clement were not acquainted with Cruickshank s paper, which had not then reached Paris, but their results confirmed his. They obtained the gas by heating zinc oxide with charcoal or graphite, or barium carbonate with charcoal, and found that it could be exploded with oxygen over oil or mercury in a eudiometer (it exploded only weaWy), giving no water but only carbonic acid gas, completely absorbed by lime water. An important experiment was... 

On 27 June 1800, Dalton read Experiments and Observations on the Heat and Cold produced by the Mechanical Condensation and Rarefaction of Air. Joule (a pupil of Dalton) says that Dalton ascertained that about 50 of heat are evolved when air is compressed to one-half its original bulk and that, on the other hand, 50 are absorbed by a corresponding rarefaction and this result can be inferred from what Dalton says, although it is not explicitly stated. The method (of adiabatic expansion) was afterwards adapted by Clement and Desormes to the determination of the ratio of specific heats of a gas. ... 

In reading the papers of Desormes and Clement after Priestley s contemporary publications we feel that we are in a new world. Cruickshank had just before them cleared up the confusion between the inflammable airs which was the main source of Priestley s numerous errors, but Priestley s mind was closed. He objected to Cruickshank s correct experiments and conclusions, and in a series of communications from 1798 to 1803 (to be mentioned later) to the Medical Repository he refused to accept a compromise by one of its editors, Mitchill, in which hydrogen was assumed to be a compound of phlogiston and heat (caloric), sulphur a phlogisture of sulphur , etc., and metals as elements. Priestley had said with pride that no person was ever more temperate, or more cautious, than I have been in the introduction of new terms considering the number of new facts that I have discovered , and inflammable air was an example of one term covering many different gases. 

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