Dr. W. C. Henry's Experiments on Gaseous Interference. 325 



activity of prepared plates of the same metal. Various modes 

 have beenproposed of interpreting these phsenomena. Dr. 

 Turner (Chemistry, 5th edit., p. 647) observes, « One would 

 be tempted to suppose that these gases act by soilinsr the 

 metallic surface, though in some respects this explanation 

 IS not satisfactory." In the Essay by Dr. Henry already re- 

 ferred to (p. 282), it is suggested that this property « is most 

 remarkable in those gases which possess the strongest attrac- 

 tion for oxygen, and it is probably to the degree'of this at- 

 traction, rather than to any agency arising out of their rela- 

 tions to caloric, that we are to ascribe the various powers 

 which the gases manifest in this respect." Finally, the latest 

 writer on this subject, Dr. Faraday, concludes (par. 655.): 

 "Whether the effect produced by such small quantities of 

 certain gases depends upon any direct action which they may 

 exert upon the particles of oxygen and hydrogen, by which 

 the latter are rendered less inclined to combine, or whether it 

 depends upon their modifying the action of the plate tem- 

 porarily (for they produce no real change on it) by investino- 

 3t through the agency of a stronger attraction than that ol" 

 the hydrogen, or otherwise, remains to be decided by more 

 extended experiments." It was in the hope of illustrating the 

 nature of these interesting phasnomena in gaseous chemistry 

 that the following experiments were instituted. 



The carbonic oxide and olefiant gases are stated by all the 

 above-mentioned inquirers to possess, in the most remarkable 

 degree, the property of interference. I have selected those erases 

 as fitter subjects for experiment than others which manifest 

 the same property, because, as Dr. Faraday testifies, they pre- 

 vent combination, without at all injuring or affectino- the 

 power oftheplatina (61-4. and 6.), and hence exhibit the^phs- 

 nomenon in its simplest form. The platina which I em- 

 ployed was in the various conditions of (1.) plates prepared 

 according to Dr. Faraday's method; (605.) (2.) sponge from 

 calcination of the ammonia-muriate, either alone or moulded 

 with Ch ma clay mlo small balls; and (3.) the black powder 

 precipitated by the addition of alcohol to the solution of proto- 

 chloride of platina in potassa, according to Liebig's process. 



1. Carbonic Oxide.— To a mixture of oxygen and hydro- 

 gen, in the proportions required to constitute water, carbonic 

 oxide was added, so as to form ^^th, y<jth, and • th of the 

 entire volume. The prepared plate when .admitted caused 

 no appreciable diminution, nor was any change observed du- 

 ring three or four hours in any of the three mixtures. The 

 loUowmg morning evident but slight diiuimitian was visible 

 in all. 



