AND MODEM PHYSICS. 



slicwn that tho value of tlio coefficient* of viscosity 

 " is tho same for air at 0*5 inch and at 30 inches 

 pressure, provided that the temperature remains the 

 same." 



It was clear also that the viscosity depended on 

 the temperature, and the results of the experiments 

 seemed to show that it was nearly proportional to tho 

 absolute temperature. Thus for two temperatures, 

 185 Fah. and 51 Fait, the ratio of the two co- 

 efficients found was T2G24; the ratio of the two 

 temperatures, each measured from absolute zero, is 

 1-2605. 



This result, then, docs not agree with the hypothesis 

 that a gas consists of spherical molecules acting only 

 on each other by a kind of impact, for, if this were so, 

 tho coefficient would, as we have seen, depend on tho 

 square root of tho absolute temperature. But Max- 

 well's result, connecting viscosity with the first power 

 of the absolute temperature, has not been confirmed 

 by other investigators. According to it we should 

 have as the relation between /*, tho coefficient of 

 viscosity at t"and ji lrt that at zero the equation 

 p = ^(1 +.003G5t). 



The most recent results of Professor Holman 

 (Philosophical Magazine, Vol. xxi., p. 212) give 



p = ,i (1 + .00275 1 .00000034 t*}. 

 And results similar to this are given by O. E. Meycr t 



Owing to an error of calculation tho actual value obtained by 

 Maxwell from tin-so observations for the coefficient of viscosity is too 

 grcut. More iccent observers have found lower values than those 

 ^i veil by him ; tho difference is thus explained. 



