Statistical mecliaiiics 



and 



(146) a*a,o„ = -i|7r {dilil'I^ 



lu like manner we get 



00 



0 



and 



Using the notation 

 ,U7) y= 



we now have: 



(148) ^X2o= 



«*«002 = ^• 



If in the expression (137) for V200 ^"^7 terms of the second order are con- 

 sidered (terms of the third order as well as those of the first and the second order 

 vanish), so is obtained 



T 



(■^^^) V200 ~ ^( ^-^000200 H~ -^000020 ~l~ -^000 00s)' 



where T denotes a certain numerical constant defined through (147). 



It follows that we here get the same expression for V200 ivhen the repulsion- 

 law of Maxwell is used, except that the numerical factor has another value. 



I have here tacitly supposed that integrals of the form a^^^, a^^, a,j„ vanish. 

 We may more generally demonstrate that a coefficient 



a... 



vanishes, as som as any one of the indices i, j or k is an odd number. 

 Let us, indeed, consider integrals of the form 



/// U' VJ W'< Fiü) dUdVd 



00 



where F is any arbitrary function of Q . 



Suppose Jc to be an odd number and substitute the same polar coordinates as 

 before. We have then to deal with integrals (regarding B) of the form 



