214 Mr. J. C. Maxwell on the Dynamical Theory of Gases. 



Hydrogen andCarbonic 

 acid. 



Observed. 



Calculated. 



Hydrogen 



and Air. 



Observed. 



Calculated. 



100 o 



•4321 



•4375 



100 







•4434 



•4375 



97-5 25 



•4714 



•4750 



95 



5 



•5282 



•5300 



95 5 



•5157 



•5089 



90 



10 



•5880 



•6028 



90 10 



•5722 



•5678 



75 



25 



•7488 



•7438 



75 25 



•6786 



•6822 



50 



50 



•8179 



•8488 



50 50 



•7339 



•7652 



25 



75 



•8790 



•8946 



25 75 



•7535 



•7468 



10 



90 



•8880 



•8983 



10 90 



•7521 



•7361 



5 



95 



•8960 



•8996 



100 



•7470 



•7272 







J 00 



•9000 



•9010 



The numbers given are the ratios of the transpiration-times of 

 mixtures to that of oxygen as determined by Mr. Graham, com- 

 pared with those given by the equation (140) deduced from our 

 theory. 



Conduction of Heat in a Single Medium (<y) . 

 The rate of conduction depends on the value of the quantity 



where £ 3 , f/7 2 , and £f 2 denote the mean values of those functions 

 of %, 7], £ for all the molecules in a given element of volume. 



As the expressions for the variations of this quantity are some- 

 what complicated in a mixture of media, and as the experimental 

 investigation of the conduction of heat in gases is attended with 

 great difficulty, I shall confine myself here to the discussion of a 

 single medium. 



Putting 



Q = M{u + %){u*-\-v 2 + iv 2 + 2uZ+2v>n + 2w^ 



+j3(p+v 2 +n}> j * (142) 



and neglecting terms of the forms f ?? and f 3 and fV when not 

 multiplied by the large coefficient k v we find by equations (75), 

 {77), and (54), 



•e(?+*? 



? 2 )J-w" 



y ■ (143) 



dx 



= -3^A 2 /3{f + ^ + ^} 



The first term of this equation may be neglected, as the rate of 

 conduction will rapidly establish itself. The second term con- 

 tains quantities of four dimensions in f, 77, f, whose values will 

 depend on the distribution of velocity among the molecules. If 

 the distribution of velocity is that which we have proved to exist 



