74 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. 



the influence of a prepared plate or of spongy platina. A mixture of one volume 

 of this gas with three of pure hydrogen, and the due proportion of oxygen, was not 

 affected by plates after fifty hours. I am inclined to refer the effect to carbonic oxide 

 present in the gas, but have not had time to verify the suspicion. The power of the 

 plates was not destroyed (640. 646.). 



655. Such are the general facts of these remarkable interferences. 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 temporarily (for they produce no real change on it), 

 by investing it through the agency of a stronger attraction than that of the hydrogen, 

 or otherwise, remains to be decided by more extended experiments. 



656. The theory of action which I have given for the original phenomena appears 

 to me quite sufficient to account for all the effects by reference to known properties, 

 and dispenses with the assumption of any new power of matter. I have pursued this 

 subject at some length, as one of great consequence, because I am convinced that the 

 superficial actions of matter, whether between two bodies, or of one piece of the same 

 body, and the actions of particles not directly or strongly in combination, are be- 

 coming daily more and more important to our theories of chemical as well as mecha- 

 nical philosophy*. In all ordinary cases of combustion it is evident that an action 

 of the kind, considered either upon the surface of the carbon in the fire, or that in the 

 bright part of a flame, must have great influence over the combinations there taking 

 place. 



657- The condition of elasticity upon the exterior of the gaseous or vaporous mass 

 already referred to (626. 627.), must be connected directly with the action of solid 

 bodies as nuclei on vapours, causing condensation upon them in preference to any con- 

 densation in the vapours themselves ; and in the well-known effect of nuclei on solu- 

 tions a similar condition may have existence (623.), for an analogy in condition exists 

 between the parts of a body in solution, and those of a body in the vaporous or gaseous 

 state. This thought leads us to the consideration of what are the respective conditions 

 at the surfaces of contact of two portions of the same substance at the same tempera- 

 ture, one in the solid or liquid, and the other in the vaporous state ; as, for instance, 

 steam and water. It would seem that the particles of vapour next to the particles of 

 liquid are in a different relation to the latter to what they would be with respect to 



^ * As a curious illustration of the influence of mechanical forces over chemical aifinity, I will quote the refusal 

 of certain substances to effloresce when their surfaces are perfect, which yield immediately upon the surface 

 being broken. If crystals of carbonate of soda, or phosphate of soda, or sulphate of soda, having no part of 

 their surfaces broken, be preserved from external violence, they will not effloresce. I have thus retained 

 crystals of carbonate of soda perfectly transparent and unchanged from September 1827 to January 1833 ; and 

 crystals of sulphate of soda from May 1832 to the present time, November 1833. If any part of the surface 

 were scratched or broken, then efflorescence began at that part, and covered the whole. The crystals were 

 merely placed in evaporating basins and covered with paper. 



