STUDIES ON THE PHENOMENA OF CONTACT. 403 



which serves to flcsii^nate, at the same time, a great number of like facts. Davy 

 soaght to explain the slow combustions which he liad observed by saying : 

 "Platina and palladium conduct heat badly, being of feeble capacities in com- 

 parison with other metals ; and in tliis, it seems to me, resides the principal 

 cause why they maintain, produce, and render sensible these slow combustions." 

 But we have seen that sundry other bodies act in the same manner as the wire 

 of platina and palladium, when they arc placed in the same conditions. M. 

 Doberciner, on the contrary, regarded the combustion of hydrogen by the influ- 

 ence of platina as "an electric eft'ect resulting from a circuit in which hydro- 

 gen represents the zinc and the platina the other metal. It is the first example," 

 he added, "of an electric circuit formed of a gaseous substance with a concrete 

 body, Avhose activity has been verified." Since then, Grove, in England, has 

 constructed his gaseous battery, of which we shall speak directly. Berzelius 

 imagines a new force generated in the contact of this tliird body, (platina;) a force 

 which he calls the catalytic, but of which he establishes no property unless it 

 be that of causing the two bodicss to combine which, before the contact of the 

 third did not react. The influence which this great man exercised in chemistry 

 has caused his theory to be blindly adopted by many chemists. Nevertheless, 

 in proportion as catalytic phcnomcuia became more common, as they began to 

 acquire the features of generalization, doubts respecting the existence of this 

 new force sprang up. And we shall endeavor, presently, to prove that this is 

 not only a gratuitous hypothesis, but that, with the knowledge even then 

 possessed regarding chemical combination, there was no need of supposing, for 

 an instant, its existence. Doebereiner was, it seems to us, much nearer the 

 truth than Berzelius, and this great chemist himself was subsequently led to 

 regard the phenomena of the catalytic force as electrical. 



Let us return now to the combination of hydrogen and oxygen under the 

 influence of platina ; and, to render things more evident, let us suppose for an 

 instant that we have a molecule of hydrogen, A, and a molecule of oxygen, B, 

 covered with neutral fluid. When we place these molecules in contact at the 

 ordinary temperature, they Avill remain neutral ; we shall observe neither chem- 

 ical phenomena, nor electrical phenomena. But let them be heated ; polarity 

 manifests itself, combination takes place, and the needle of a galvanometer will 

 sufficiently attest what is passing. By the action of the heat the two molecules, 

 A and B, become the one positive, the other negative, in relation to one another. 

 At the instant when the combination takes place the hydrogen gives off the 

 negative fluid, the oxygen the positive fluid, and these two fluids passing 

 into the wires of the galvanometer move the magnetic needle. There are 

 here, then, two neutralizations of fluids; one in the water, formed by the com- 

 bination ; the other by the fluids given off. 



This phenomenon which we have just been examining is the type of what is 

 callcid combustion. Now, what heat has effected in this case the presence of a 

 third body may likewise effect. This third body has tlic power, by its presence 

 alone, of exciting "combustion" at a temperature much lower than that which 

 is necessary for the production of this phenomenon when this third body is not 

 fresent. It effects this by ii phenomenon of polarity identical with that which 

 is observed in every other chemical reaction. 



Before proving this by experiment, I shall show, with the help of a small 

 diagram, what passes under these circumstances. Let us imagine the three 

 bodies, hydrogen, oxygen, and platina sponge, in presence of each other: 



