new Mode of producing Fire. 1 1 



that an opposition may exist between the noble and inferior 

 metals, so far that the latter are favourable to the decompo- 

 sition, and the former to the union, of gases. But this is very 

 doubtful : for without considering that chemical combina- 

 tion and decomposition are not different in principle, and are 

 under most circumstances inseparable, those very noble 

 metals and their oxides are the most powerful agents in the 

 decomposition of oxygenated water, that is, the expulsion of 

 its oxygen with the evolution of caloric and light. The ex- 

 periment with the aphlngistic lamp, which is the very reverse of 

 M. Thenard's experiment with ammonia, most easily succeeds, 

 next to platinum, with iron wire ; in which therefore the iron, 

 which promotes the decomposition of the ammonia as well as of 

 the prussic acid, at an increased temperature, also favours the 

 union of oxygen and hydrogen at the same elevated tempera- 

 ture. It is not to be denied that the experiment with the aphlo- 

 gistic lamp depends also on the fullness of the points of con- 

 tact ; and that we therefore find the union of the gases to be 

 favoured by the same circumstance by which the formation of 

 crystals is promoted. When attentively considered, chemical 

 and crystalline attraction will appear to be the same, as it is 

 well known that every chemical precipitate appears in a cry- 

 stalline form under the microscope. This is illustrated by a 

 very interesting experiment made by my friend M. Vogel, a 

 very ingenious chemist, formerly a resident at Bayreuth, whose 

 early death was a great loss to the science. He first observed 

 the combination of oxygen and hydrogen at a low tempera- 

 ture, under the influence of charcoal. It is true, that in this 

 experiment charcoal impregnated with hydrogen must be em- 

 ployed, by which the atmospheric air becomes at the same time 

 deoxygenated. If, however, one should be inclined to reduce 

 that power of the charcoal to a mechanical principle, it should 

 also be considered, that the hydrogen will be more perfectly di- 

 vided, and most fully in contact with the oxygen, when mixed 

 with the latter in a gaseous form, than when previously absorbed 

 by the charcoal : and when we consider, moreover, that hydro- 

 gen not only adheres mechanically to the charcoal, especially 

 when absorbed with water, but becomes condensed, it ought 

 not to be forgotten, that hydrogen and oxygen may be greatly 

 condensed in the gas blow-pipe, and will remain for years in 

 that state, without combining with each other, when the com- 

 pression is effected slowly and quietly. In this interesting 

 experiment of M. Vogel likewise we find that the many points 

 of contact effect the union of the gases. The effect, how- 

 ever, in this instance is more slow and feeble than in the ox 

 periment of Dceberciner. 



B 2 This 



