0)1 the neio Experiments o/'M. Doebereiner. 285 



but it caused the formation of water at a temperature of 

 about 464° F. 



Gold and silver in thin leaves act only at high temperatures, 

 but always under that of the ebullition of mercury. Silver is 

 less efficacious than gold. A thick lamina of the latter does 

 indeed act, though with more difficulty than the leaves ; and 

 a thick lamina ol' silver has an action so weak as to be doubt- 

 ful. 



We have also tried if other combinations could be effected 

 by the same means. Carbonic oxide and oxygen combine, and 

 nitrous gas is decomposed by hydrogen at the common tempe- 

 rature by contact with platinum in the spongy state. The fine 

 leaves of the same metal do not produce the combustion of the 

 first-mentioned gas, exceptat a temperature above 572° F. Gold 

 leaf causes it also at a degree near the boiling of mercury. 



Finally, olefiant gas mixed with a suitable quantity of oxygen 

 is completely transformed into water and carbonic acid by 

 platinum in the spongy state, but only at a temperature of more 

 than 572° F. 



We would call to mind, on the subject of the preceding ex- 

 periments, that one of us showed long smce that iron, copper, 

 gold, silver, and platinum, had the property of decomposmg am- 

 monia at a certain temperature, without absorbing either of the 

 principles of that alkali ; and that this property appeared in- 

 exhaustible. Iron possesses it in a higher degree than copper, 

 and copper more than silver, gold, and platinum, in proportion 

 to the surfaces. 



Ten grammes of iron wire are sufficient for decomposing, 

 within a few hundredths, a current of ammoniacal gas rather 

 rapid, and kept up for eight or ten hours, without the tem- 

 perature passing the limit at which the ammonia completely 

 resists decomposition. Thrice that quantity of platinum wire of 

 the same thickness, does not produce nearly a like effect even 

 at u higher temperature. 



The remarkable results of this experiinent depend, perhaps, 

 on the same causes as those which make gold and silver effect 

 the combination of hydrogen and oxygen at 572° F., solid pla- 

 tinum at 518° F., and spongy platinum at the ordinary tempe- 

 I'atm'e. 



Now, if we observe that iron, which so well decomposes 

 annnonia, does not effect, or but with difficulty, the combi- 

 nation of hydrcjgen with oxygen, and that platinum, which is 

 so effective" for tliis latter combination, produces but with dif- 

 ficulty the decomposition of annnonia, we are led to believe 

 that among the gases some have a teiuleiicy to uuite under 

 the influence oi' ihc metals, while others hnvc a tendency to 



separate ; 



