SECTIONAL TRANSACTIONS.—B. 301 
SECTION B.—CHEMISTRY. 
(For references to the publication elsewhere of communications entered in the 
following list of transactions, see page 389.) 
Thursday, August 27, 
1. Discussion on Surface Catalysis. 
Dr. E. K. Ripeat.—The Influence of Surfaces in Chemical Reactions. 
Although adsorption at surfaces may result in the formation of multimolecular 
films, the adsorption of the first layer is attended with a much greater decrease in 
free energy, and it is in this film that chemical reaction at surfaces takes place. This 
conception has been amplified and extended in two directions. We find accumulated 
evidence for the conception of orientation and distortion of the molecules in this 
primary layer ; evidence for the persistence of such orientation but to a less marked 
extent in the multimolecular secondary layer exists. 
Again, only asmall fraction of the surface is catalytically active. Both by the method 
of calculation of the number of effective impacts as well as by the method of selective 
poisoning, the extent of the active surface can be determined. In this way it has 
been shown that only 0.01 per cent. of a carefully prepared active nickel surface is 
effective in promoting the combination of ethylene and hydrogen. About 0.05 per 
cent. of the surface of active sugar charcoal is autoxidisable, and 40 per cent. can 
catalyse the oxidation of oxalic acid. Great improvements in catalytic efficiency are 
thus to be anticipated. The specific effects of promotors can be determined in this way, 
thus, the active area of iron activated blood charcoal is over twenty times as active 
as the active area of sugar charcoal in promoting the oxidation of oxalic acid, although 
the activity per gm. is fifteen and per sq. cm. is only some three times as great. 
The activation by alternate oxidation and reduction can be ascribed to an exten- 
sion of the space lattice of the metal. 
Future work must decide whether active areas are distributed according to the 
laws of probability or are associated with definite atomic configurations. 
In addition, more information is required on the mechanism of activation ; our 
_ present evidence is not sufficient to decide between two hypotheses. In one we can 
regard every molecule which strikes the active patch with a kinetic energy in excess 
of a critical value as undergoing reaction; in the other, we may regard adsorption 
as taking place as a primary action which is followed by activation, by collision, or 
possibly by collision and by radiation. 
Mr. C. N. HinsHetwoov.—Surface Catalysis. 
In homogeneous changes one of the most important factors determining the rate 
which a reaction can attain at a given temperature is the energy of activation. This 
can be found from the influence of temperature on the reaction velocity. An analogous 
quantity must play avery important réle in heterogeneous reactions, but its determina- 
tion is a more difficult matter. True and apparent heat of activation are distinguished, 
and the relation between them shown. In certain examples the true heat of activation 
can be found. 
The relation between the kinetics of certain reactions proceeding (a) homogeneously, 
(6) on the surface of catalysts, is discussed. The application of the quantum theory 
to these phenomena is also discussed. 
An explanation of some of the phenomena connected with the complete desiccation 
of chemical systems is suggested. 
Dr. W.G. Patmer.—A New Method for the Study of Adsorption Films. 
Further progress towards an explanation of the mechanism of heterogeneous 
catalysis is heavily impeded by the meagreness of our knowledge of the properties of 
adsorption films. This has come about chiefly because the examples of adsorption most 
open to experiment are just those in which a great complexity of relations between 
