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XVIII. On Catalysis, and the Nomenclature of Oxides. By 

 Thomas Bayley, Assoc. R. C.Sc.L, Demonstrator of Prac- 

 tical Chemistry, Analysis, and Assaying in the Mining School, 

 Bristol*. 



AMONG, the most remarkable ; and at first sight the most 

 inexplicable, of the heterogeneous class of reactions 

 known as catalyses are the decompositions undergone by hy- 

 drogen peroxide in contact with certain substances. But on 

 further examination these phenomena afford us the means of 

 explaining and differentiating a considerable number of similar 

 reactions and of effecting a classification of them. As is 

 well known, hydrogen peroxide, although one of the least 

 stable of well-defined compounds when in the concentrated 

 form, becomes when diluted, especially in the presence of acids, 

 much less subject to decomposition. 



A solution of peroxide of hydrogen, sufficiently dilute to 

 remain unaffected for a considerable time when mixed with 

 dilute solution of sodic hydrate, may be used effectively in the 

 preparation of the peroxides of several metals. If to a solu- 

 tion of a cobalt salt, sodic hydrate and then hydrogen peroxide 

 be added in the cold, the hydrate of cobalt at first precipitated 

 becomes rapidly blackened, and a hydrated peroxide of vari- 

 able composition is produced. Almost- immediately a rapid 

 evolution of oxygen takes place ; and before long the whole of 

 the excess of peroxide of hydrogen is decomposed, the cobalt 

 peroxide, however, remaining unchanged. Under similar cir- 

 cumstances salts of lead and manganese give the same reac- 

 tion, namely the formation of a dark-coloured peroxide and 

 the decomposition of the excess of hydrogen peroxide. With 

 copper the effects are somewhat different : on the addition of 

 the hydroxyl the suspended blue hydrate of copper assumes a 

 transient yellowish-red colour, but almost immediately resumes 

 its original appearance, while the evolution of oxygen proceeds 

 as in the former cases. Nickel, although possessing properties 

 remarkably resembling those of cobalt, under the influence of 

 the mixture of soda and hydroxyl is not peroxidized ; the sus- 

 pended green hydrate is permanent, and the liquid retains for 

 a long time the properties of a solution of hydrogen peroxide. 

 But although the latter has not the power of peroxidizing 

 nickel salts, the hydrated peroxide of nickel, formed by other 

 means, effects almost as readily as does the corresponding 

 cobalt compound the destruction of hydroxyl. It is this dif- 

 ference between the behaviour of nickel and cobalt that affords 

 the key to these remarkable phenomena. It is evident, and it 

 * Communicated by the Author. 



