319 MM, DuJoNg and Thenard on the [Nov* 



Article X. 



On the Property which some Metals possess of facilitating the 

 Combination of Elastic Fluids. By MM. Dulong and 

 Thenard.* 



Prof. Dobereiner, ofthellniversityof Jena, has discovered 

 one of the most curious phenomena which physical science is 

 susceptible of unfolding. We are unacquainted with his labours 

 excepting by the announcement in the Journal des Debats of the 

 24th of August last, and which does not give a very correct 

 account of them, and from a letter of M. Kastner to Dr. Liebeg, 

 which the latter, now at Paris, has communicated to us. In this 

 it is stated, that platinaf in a spongy mass occasions the combi- 

 nation of oxygen and hydrogen at common temperatures, and 

 that the extrication of heat which results from the action ren- 

 ders the metal red-hot. We were anxious to verify so surprising 

 a fact, and found it perfectly correct. As the experiment may 

 be made with the greatest ease, we shall perform it before the 

 Academy. 



Not being acquainted with the researches which the author of 

 this beautiful experiment has undoubtedly undertaken in order to 

 develope the theory of it, we could not refrain from making some 

 experiments with this view ; and although we have not yet suc- 

 ceeded, we think that the results of the observations which we 

 have already made are not unworthy the attention of the Aca- 

 demy .J 



In the experiment which we have made, the spongy platina 

 became red-hot when placed where the hydrogen escaping from 

 the reservoir became intimately mixed with the air. It was 

 evident from this, that detonation would occur by immersing a 

 piece of the spongy platina in a mixture of two volumes of 

 hydrogen and one volume of oxygen ; and this was confirmed 



♦ Annalcs de Chimic et de Physique, tome xxiii. p. 440. 



■|- Since the printing of this notice, the authors have observed first, that pallatlium in 

 a spongy mass is capable of inflaming hydrogdii as platina does ; secondly, that iridium 

 in the same form became very hot, and pro<luced water ; thirdly, that cobalt and nickel 

 in mass, at about 57t° Falir. effected die unicn of hydrogen and oxygen ; fourthly, that 

 spongy platina at the common temperatures formed water and aumionia with nitrous 

 gas and hydrogen, and acted upon a mixture of hydrogen and pretoxide of azote. 



J The hydrogen lamp invented by M. Gay-Lussac is extremely convenient for per- 

 forming this experiment. The electrophorus is to be removed, or the conductors are 

 merely to be detached ; a piece of light spongy platina is to be placed at the distance of 

 about two centimetres from the aperture at which the gas escapes ; when the cock is 

 turned, tlie jet of hydrogen gas comes mixed with atmospheric air to the surface of the 

 spongy platina. It then soon became red-hot, arid the hydrogen gas once inflamed 

 continues to burn as it escapes, as if it had been lighted by the spark. 



In the absence of the lamp, the common apparatus used for preparing hydrogen gas 

 may be employed. It is however requisite to take care that the gas passes through a 

 very small aperture, in order that it may more intimately mix with atmospheric air, 



