378 On the Combination of Elastic Fluids, [Nov/ 



ful than gold. A bar of gold acts, but with greater difficulty 

 than the leaves ; a thick bar of silver acts so feebly as to be 

 questionable whether it has any power. 



We have examined whether other combinations could be 

 effected by the same method. Oxide of carbon and oxygen 

 combine, and nitrous gas is decomposed by hydrogen at com- 

 mon temperatures by spongy platina ; thin sheets of this metal 

 require a temperature of above 672° of Fahr. to cause the two 

 former gases to combine. Gold leaves effect it also at a tem- 

 perature approaching that of boiling mercury. 



Lastly, defiant gas mixed with a proper quantity of oxygen is 

 completely converted into water and carbonic acid by spongy 

 platina, but only at a temperature above 572° of Fahr. It will 

 be remembered on the subject of the preceding experiments, 

 that one of us proved a long time since, that iron, copper, gold, 

 silver, and platina, possess the property of decomposing ammo- 

 nia at a certain temperature, without absorbing any of this 

 alkali, and that this property appeared to be inexhaustible. Iron 

 possesses it in a greater degree than copper, and copper more 

 than silver, gold, or platina, the surfaces of all being equal. 



One hundred and fifty-four grains of iron wire were sufficient 

 to decompose within a few hundredths a current of ammoniacal 

 gas rather rapidly evolved, and continued during eight to ten 

 hours, without the temperature exceeding the limit at which 

 ammonia completely resists. Three times the quantity of platina 

 wire of the same size scarcely produced an equal effect, even at 

 a higher temperature. 



The remarkable results of this experiment depend perhaps 

 upon the same causes as those which occasion gold and silver 

 to effect the combination of hydrogen and oxygen at 572° Fahr. ; 

 platina in mass at 518° Fahr. ; and spongy platina at common tem- 

 peratures. If then we observe that iron, which so readily decom- 

 Eoses ammonia, does not effect, or effects with difficulty, the com- 

 ination of hydrogen with oxygen, and that platina, which is so 

 powerful in the latter case, scarcely decomposes ammonia, we 

 are induced to suppose that some gases have a tendency to com- 

 bine under the influence of the metals, and others to separate ; 

 this property varying on account of the nature of each. Those 

 metals which produce one of the effects most perfectly are inca- 

 pable of producing the other, or in a less degree. 



We shall refrain from offering the conjectures which these 

 singular phenomena have given rise to, until we have completed 

 the experiments which we have undertaken to verify them.* 



♦ Prof. Dtibereiner's experiment has also heen verified by l\Ir. Faraday, who has 

 given the following notice of it in No. 31, of the Journal of Science. " It consists in 

 passing a stream of hydrogen against the finely divided platina, obtained by heating the 

 muriate of ammonia and platina. In consequence of the contact, the hydrogen inflames. 

 Even when the hydrogen does not uiflame, it ignites the platina in places ; and I find 

 that when the hydrogen is passed over the platinum in a tube, no air being admitted, still 

 the platinum hwts in the same manner.** 



