Again,

(4.128)

Putting                                     where

(4.129)

(4.130)

Now,

(4.131)

So, 

(4.132)

For                                              x = 1,

(4.133)

For                                              x = ∞,

(4.134)

The number of molecules having x- component velocities between x and α,

(4.135)