Intelligence and Miscellaneous Articles. 413 



ON THE SOLUTION OF HYDROGEN IN METALS, AND THE DECOM- 

 POSITION OF WATER BY IRON. BY MM, L. TROOST AND P. 

 HATJTEFETJILLE. 



In previous researches on the alloys formed by hydrogen*, we 

 have pointed out the characters by which these definite combina- 

 tions may be distinguished from the solutions of hydrogen in the 

 metals. "We have seen that besides potassium, sodium, and palla- 

 dium, which can combine with hydrogen, there are other metals 

 which simply dissolve this gas. The number of those which pos- 

 sess this last property appears to be considerable. 



We shall see that iron, nickel, cobalt, and manganese, which are 

 united by the analogy of their chemical properties into a natural 

 group, present great similarities in their behaviour in the presence 

 of hydrogen at various temperatures. As the facility with which 

 they absorb or give out hydrogen depends largely on their physical 

 state, it is necessary, in order to account for the differences observed, 

 to investigate these metals successively in ingots, in thin plates, and 

 in the pulverulent condition. 



I. Nickel. — An ingot of pure nickel, cast in lime, was submitted 

 for twenty-four hours, at a red heat, to the action of a current of 

 hydrogen gas, and then cooled slowly in the gas. The volume of 

 hydrogen extracted from it at a red heat in vacuo was one fifth of 

 the volume of the metal. 



Some laminae of nickel, obtained by decomposing with the pile 

 the double sulphate of nickel and ammonia, were heated in a va- 

 cuum to 200° C. ; they gave out forty times their volume of hydro- 

 gen t. On afterwards being heated to near 200° in a current of 

 hydrogen and slowly cooled in this gas, they absorbed sixteen times 

 their volume of it, which they gave up in vacuo at 200°. The same 

 laminae, placed for twenty-four hours at the negative pole of a vol- 

 tameter, absorbed about ten times their volume of hydrogen J. 



The pulverulent nickel was obtained by reducing the oxide or a 

 mixture of oxide of nickel and alumina by means of hydrogen at 

 300°. Nickel thus prepared is pyrophoric, as Magnus has shown §, 

 In a vacuum it gives up a certain quantity of hydrogen at the ordi- 

 nary temperature ; but to expel this gas entirely a dull red heat is 

 requisite. The total volume of gas discharged is about one hundred 



* Comptes Rendus de VAcad. des Sciences, vol. lxxviii. pp. 686, 807. 

 Phil. Mag. S. 4. vol. xlvii. p. 397. 



t The gas analyzed did not give any perceptible quantity of nitrogen. 

 Some laminae prepared in the same way, then washed and dissolved in 

 chlorhydric acid, gave traces of ammonia. 



X M. Raoult states (Comptes Rendus, vol. lxix. p. 826) that the impure 

 porous nickel cubes of commerce, when placed at the negative electrode of 

 a voltameter, absorb 165 volumes of hydrogen, which they gradually dis- 

 engage at the ordinary temperature. The same cubes electroplated with 

 pure nickel did not appear to him to disengage any appreciable quantity 

 of gas. 



§ Annates de Chimie et de Physique, 2 serie, vol. xxx. p. 103. 

 Phil. Mag. S. 4. Vol. 49. No. 326. May 1875, 2 F 



