Dr.W. C. Henry's Experiments on Gaseous Interference. 331 



of plate, sponge, or powder; the powder presenting only an 

 infinitely larger extent of surface for gaseous contact than the 

 plate or sponge. Hence the tendencies of the constituents of 

 defiant to unite with oxygen, which are evidenced by com- 

 bination to considerable amount in presence of the powder, 

 may be inferred to be operative, though less effectively, on 

 the surface of the same metal under other forms ; and viewed 

 in connexion with the unequivocal proofs of the nature of the 

 interference of carbonic oxide, these tendencies may be ad- 

 mitted to furnish an adequate explanation of the more feeble 

 interference of olefiant gas*. 



The influence of temperature in quickening the action of the 

 sponge or powder on mixtures of olefiant and oxygen strongly 

 confirms this view, when taken in connexion with a pecu- 

 liarity observed in the mode of interference of olefiant gas. 

 Thus it has been stated that olefiant mingled in equal bulk 

 with explosive mixture did not prevent instant action ; and 

 that it began to interfere only when much of the oxygen and 

 hydrogen had combined together, with the disengagement of 

 great heat. The interfering power of olefiant gas, feeble at 

 atmospheric temperatures, is then greatly augmented by heat, 

 which has been already shown to determine the separate com- 

 bination of the elements of olefiant with oxygen, and which is 

 well known to exalt chemical affinity. 



In recapitulation, it may be stated that carbonic oxide in- 

 terferes with the action of platina upon mixtures of oxygen 

 and hydrogen, by virtue of its stronger affinity for oxygen, 

 which causes it slowly to take the larger portion of that gas. 

 Olefiant gas, which at common temperatm-es has a weaker at- 

 traction for oxygen than hydrogen, suspends the combining 

 tendencies of those two gases, only when its volume greatly 

 exceeds that of the mixture, in which case the weaker affinity 

 is aided by a greater number of atoms. Even with this advan- 

 tage olefiant is unable to appropriate the oxygen to itself, but 

 only retards its union with hydrogen by opposing a weaker 

 attractive tendency. 



Nor is the admission of attractive forces between the par- 

 ticles of mixed gases, even when not manifested by any visible 

 action (as between oxygen and the elements of olefiant gas), 

 inconsistent with what is known of chemical affinity as ope- 

 rating in the solid and liquitl forms of matter. In the eighth 

 of his admirable series of memoirs on electro-chemistry, Dr, 

 Faraday has shown that zinc, having its surface thinly amal- 



* The interfering power of carbonic oxide as respects the action of the 

 platina balls is eighteen times as great as that of defiant; carbonic oxide 

 in the proportion of ,',th interfering as conipletoly as olefiant in that of 

 ;ths of the mixture. 



2Q2 



