52 



MOLECULAK MOTION AND ITS ENERGY 



26 



magnitude is equal to that of the abscissa x, and for the 

 unit of speed that value is chosen which is the most 

 probable. 



This graphic representation of the law lets us easily see 

 that the values of the speed that occur with any considerable 

 frequency are only slightly different from that of greatest 

 probability, whence we might conclude that the idea of all 

 the molecules possessing equal speed is really approximately 

 admissible. For a speed which is three or even only two 



to 



08 



O 6 



0-4- 



oz 



1. 



FIG. 2 



and a half times as great as the most probable speed has 

 an almost vanishing probability, as a glance at the figure 

 shows, so that no speeds can in fact occur which con- 

 siderably surpass this value. And this is the case, too, with 

 jadarkedly smaller speeds. 



Pirogoff l has therefore gone so far as to assume that 

 the values of the molecular speed which really occur lie 

 between fixed limits, both the very large and the very small 

 values of the speed being cut out by some equalising action 

 such as a resistance or something of that kind. We may, 

 in fact, as we easily see from the curve, determine such 



1 Fortschr. d. Physik, 1886, 42. Jahrg. 2. Abth. p. 241. 



