1855.] on Catalytic Action and Combustion. 69 



course. It is just possible that it may ultimately prove to be a truth 

 in relation to those cases, but it does not, at present, explain them. 



3. Playfair observes, " There are many instances where catalytic 

 decompositions ensue, where there is no intestine motion in the 

 atoms of the exciting body. Hence we cannot do more than 

 consider motion as favourable to the development of dormant 

 affinities." He should, perhaps, have said, "Where there is no 

 apparent intestine motion ;" and there may be an undesirable am- 

 biguity in the phrase, " favourable to the development of dormant 

 affinities." In his essay on the subject, (a monument of learning 

 and industry,) he concludes, that " the catalytic body is a substance 

 which acts by adding its own affinity to that of another body, or 

 by exerting an attraction sufficient to effect decomposition under 

 certain circumstances, without being powerful enough to overcome 

 new conditions, such as elasticity and cohesion, which occasionally 

 intervene, and alter the expected result." (Thus, for instance, A 

 and B have each separately an affinity for the element (e) of a 

 third body E, but neitlier, separately, can tear it from its combina- 

 tion with E : — the joint attraction of A and B mai/ be sufficient to 

 release it ; but the released element will not therefore necessarily 

 combine with A and B.) 



4. Faraday, and others, consider that many cases of catalysis are 

 due to the powerful condensation of liquids, vapours, and gases, 

 upon the surface of the catalyzing body. This view is of great 

 importance, but not (as yet) equal to the explanation of nearly all 

 the phenomena. Some of the arguments in favour of it may be 

 found in a consideration of the probable mechanical condition of 

 platinum, owing to the method of manufacture, the ascertained 

 absorptive power of certain catalyzing agents, and the probable 

 condensation of water in sulphuric acid. 



5. De la Rive explains the particular case of the combination of 

 hydrogen and oxygen on the surface of platinum, by supposing 

 that the platinum is oxidated on its surface, and the oxide con- 

 tinuously reduced by the hydrogen, water resulting. (See Gmelin's 

 Chemistry, published by the Cavendish Society, Vol. II. p. 56.) 



Mr. Ashby then described his own researches on catalytic com- 

 bustion. If the sesquioxides of chromium, nickel, cobalt, manga- 

 nese, and iron, be laid upon wire-gauze (about 60 meshes to the 

 inch-linear,) then warmed in the flame of a spirit-lamp, and laid 

 over capsules nearly full of alcohol, pyroxylic spirit, ether, or other 

 similar substances, they will burst into glow and catalyze the vapours 

 which rise into them, as long as the supply continues- Warm 

 Cr^ O3 will inflame a jet of hydrogen in contact with air. The sesqui- 

 oxide of iron is peculiarly available for operations on any scale, 

 however large, and those specimens are to be preferred which have 

 the least density. A catalytic lamp was exhibited, by which spirit 

 or benzole may be consumed by the catalytic glow for laboratory 



