Desormes

Courtois noticed that the new substance did not readily form compounds with oxygen or with carbon, that it was not decomposed at red heat, and that it combined with hydrogen and with phosphorus. He observed that it combined directly with certain metals without effervescence and that it formed an explosive compound with ammonia. Although these striking properties made him suspect the presence of a new element, he was too lacking in self-confidence to attempt a thorough investigation in his poorly equipped laboratory and too poor to take the time from his business (11). He therefore asked two of his Dijon friends, Charles-Bemard Desormes and Nicolas Clement, Desormes future son-... 

While Desormes devoted most of his time to applied chemistry, Clement (1779—1841) carried out a classical research in which he prepared the new substance and made a thorough study of its properties. In his report in 1813 he wrote ... 

Although Courtois discovered iodine in 1811, the announcement by Clement and Desormes was not made until two years later. Therefore, the centenary was observed in 1913. 

Historical.—This process had its origin in the early preparation of sulphuric acid by the oxidation of sulphur dioxide with nitric acid, for which operation lead chambers were first introduced in 1746 by Roebuck of Birmingham. In 1793 Clement and Desormes showed that under proper conditions the nitric acid aids the oxidation, which is in the main effected by atmospheric oxygen, and the injection of steam having already been introduced in 1774 by de la Follie, the basal chemical process was much the same as to-day. Gay-Lussac s tower was first suggested by that chemist in 1827 and was first used in 1835, being introduced into Britain in 1844. J. Glover constructed his first tower at Newcastle in 1861. 

According to Chugaev, the study of Clement and Desorm was the second piece of evidence in favour of the possible existence of a new class of reactions (catalytic). The first piece was the Dutch chemists study of the decomposition of ethyl alcohol to water and ethylene in the presence of silica or alumina. 

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... 

Show that this is essentially the basis of the Clement and Desormes method for determining 7 for gases [equation (10.11)]. 

Iodine was the second halogen to be discovered. It was first observed by Courtois, a manufacturer of nitre, in 181 r, but this was not announced until two years later by Clement and Desormes. Like so many other important discoveries that of iodine is what is popularly called accidental . That is to say it was not the result of a specific search for the element, but of a chance observation by an intelligent observer. 

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. 

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