Page:Elementary Principles in Statistical Mechanics (1902).djvu/126

102 If their values are varied, we shall have by differentiation, if $$n > 2$$, (Since $$e^\phi$$ vanishes with $$V$$, when $$n > 2$$, there are no terms due to the variations of the limits.) Hence by (269)  or, since   Comparing this with (112), we get  The first of these equations might be written  but must not be confounded with the equation  which is derived immediately from the identity