220 THE RANGE OF NATURE's OPERATIONS. 



When by this or other means we have attained the power of view- 

 ing events from the molecular standpoint, we l)egin to perceive that 

 chemical reactions, even those that occur with explosive violence, are 

 far from being the sudden events they seem to ordinary human appre- 

 hension. 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 neighbors 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 record 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 hurr}^ when we 

 view them from the molecular standpoint, as are the acts of human 

 artisans or of other animals while accomplishing some piece of work; 

 and they are, relatively speaking, persisted in for an almost immeas- 

 urably longer time, inasmuch as the fifth of a thousandth of a second 

 in the molecular world corresponds to something like one thousand 

 nine hundred 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 out- 

 come 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 circumstances 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 game. It must be an unusual experience for a human being 

 to be witness to so rare an event. The probability of it is only 1 in 

 13,060,700,000. Yet so great is the number of molecules in a gas and 

 so frequent their encounters that some millions of cases occur every 

 second in every cubic micron of the air about us in which an encounter 

 between molecules has taken place under conditions as exceptional as 

 the above; and equally unusual events probably occur some thousands 

 of times more frequently in the encounters between the molecules of 

 two liquids or of a liquid and a solid. It is thus that chemical reac- 



