94 Scientific Proceedings, Royal Dublin Society. 
When by this or other means we have attained the power of 
viewing events from the molecular standpoint, we begin to perceive 
that chemical reactions, even those that occur with explosive 
violence, are far from being the sudden events they seem to ordinary 
human apprehension. What is really occurring in nature is a 
protracted and eventful struggle between the members of two 
opposing armies, each individual of which has his own personal 
history during the struggle, and is fully occupied with his own 
acts, which are, perhaps, as many, as various, and as different from 
those of his neighbours as are the thoughts and acts of the 
individual soldiers during the progress of a battle. 
What comes under the observation of a chemist is the state of 
things which preceded this eventful period, and that other state of 
things which followed it. As to what nature has been really 
doing, his record is a blank. It is not unlike the inscription one 
often sees upon tombstones, “ Born in such a year; died in such 
another,”’ while the real event, the intervening life, is passed over 
in silence. 
How, then, ought the student of Molecular Physics to regard 
the incidents of the eventful period of a chemical reaction? ‘The 
incidents of the operations that are then going on are vastly more 
numerous, are probably as various, and are done with as little 
hurry when we view them from the molecular standpoint, as are 
the acts of human artizans or of other animals while accomplishing 
some piece of work ; and they are, relatively speaking, persisted 
in for an almost immeasurably longer time, inasmuch as the fifth 
of the thousandth of a second in the molecular world corresponds 
to something like 1900 years in ours. 
An estimate of this kind is of service, because it leads us to see 
that biological and chemical processes, even where they seem to us 
to take place with suddenness, are from the molecular standpoint 
protracted events consisting of individual transactions, each of 
which can only occur when the opportunity presents itself: they 
are not the outcome of the ordinary current of molecular events, 
but, on the contrary, each step of progress in them may have 
to wait long for some very exceptional combination of circum- 
stances to arise. The present writer once saw doublets thrown 
thirteen times in succession with unloaded dice, at the close of 
one game of backgammon and at the beginning of the next 
