32 Proceedings of Royal Society of Edinburgh. [sess. 
the proportion of the time taken to transform a given proportion 
of the total number of molecules is in a unimolecular reaction 
independent of the volume, whilst in a bimolecular reaction it 
varies inversely as the volume. By dilution, then, we should 
greatly diminish the actual rate of the bimolecular reaction as 
compared with that of the unimolecular reaction, and its disturb- 
ing influence would become apparent. Even if it did not, we 
should at least be able to assign an inferior limit to the rate of the 
rapid reaction. No graded action of this kind has hitherto been 
investigated, but a careful search may reveal one. 
