JSatarSs Operations which Man is competent to Study. 471 



to time will need to be greater than that with respect to space. 

 A good magnification for many purposes is a magnification of 

 all lengths by a nno-ten, and a magnification of the durations 

 by either three or six uno-fourteens *. (See Scientific Pro- 

 ceedings R. D. S. vol. viii. p. 372 ; or Philosophical Magazine 

 for October 1895, p. 381.) 



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 a"e 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 inter- 

 vening 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 



* The magnification of molecular intervals by a uno-ten may be called 

 standard magnification of molecular events ; because it means the repre- 

 senting of molecular events which require to be recorded in Group D by a 

 model of them so large that it records them in the corresponding parts of 

 Group C, the group of magnitudes with which we are most familiar. 



A magnification of molecular magnitudes which is a thousandth, or 

 a ten-thousandth part of tins standard, will often be found useful. 

 On the former of these scales chemical atoms may be represented by 

 beads, on the other by very fine sand used in hour-glasses, while in the 

 standard model the chemical atoms are somewhat like quadrupeds of 

 various sizrs crowded together. 



The magnification of the durations by 3 XIV (three uno-fourteens) 

 means that each micron of time becomes a second, so that an event in the 

 molecular world which occupies a fraction of a micron of time is repre- 

 sented by an event of the same kind in our model which occupies the same 

 fraction of a second. This, in the case of a great number of molecular 

 events, brings the events occurring in the model within the range of human 

 perceptions. If the time magnification is by 6 XIV (six uno-fourteens), 

 a molecular event that occupies some fraction of a micron of time is 

 represented by an event in the model which occupies the same fraction of 

 two seconds ; and this is sometimes convenient where we wish to compare 

 molecular motions with the motions of pendulums or of the limbs of 

 animals, since a pendulum which beats seconds is one whose periodic time 

 is two seconds. 



