A Jiew and Curious variety of Combustion. 389 



tJna, with an equality of surface. Ten grammes of iron wire 

 is sufficient to decompose, within a few hundredths, a pretty- 

 rapid current of ammoniacalgas, kept up during eight or ten 

 hours, without the temperature passing the hmit at which 

 the ammonia resists decomposition. Three times the quan- 

 tity of platina wire produces far less effect, even at a high- 

 er heat. 



These remarkable results depend, perhaps, on the same 

 causes as those which occasion gold and silver to effect the 

 combination of oxygen and hydrogen at 300**, platina in 

 mass at 270°, and platina in sponge at common tempera- 

 tures. Now, if it is observed, that iron which decomposes 

 ammonia so readily, effects with somuch difficulty the union 

 of oxygen and hydrogen; and that platina which is so effi- 

 cacious in this combination, hardly decomposes ammo- 

 nia, we are induced to believe that among the gases, 

 some tend to unite under the influence of metals, while oth- 

 ers tend to separate, and that this property varies according 

 to the nature of each. Those of the metals which produce 

 one of these effects produce the other only in a very small 

 degree. Jinn, de Chimie, Aug. 1823. 



In the original paper of Dobereiner, (translated in Til- 

 loch's Mag. for Octob.) he remarks, " What useful applica- 

 tions of this discovery may be made in Oxymetry, the syn- 

 thesis of water, &jc. I shall hereafter state more circum- 

 stantially. I shall at present merely observe, that the en- 

 tire phenomenon must be considered as an electric one, 

 that the hydrogen and platinum form a Voltaic combina- 

 tion, in which the former represents the Zinc ; — the first es- 

 tablished instance of an electric alternation formed by an 

 elastic fluid, and a solid substance, the application of which 

 will lead to further discoveries." 



In another letter, dated Aug. .3d, 1823, he says, " If hy- 

 drogen gas be suffered to issue from aGazometer tiirough a 

 Capillary tube bent downwards, upon the platinum con- 

 tained in a small glass funnel, sealed at the bottom, so that 

 the stream may mix with the atmospheric air before it comes 

 in contact with the platinum, which is effected when the 

 tube is from 1 to li or 2 inches distant from the platinum, 

 the latter becomes almost instantly red, and white hot, and 

 remains so, as long as the hydrogen continues to flow 



