Remarks on M. Mossotti's Theory of Molecular Action. 385 

 _ ■• /*/*/* ftf d x 1 dy 1 d z 1 



b "J J J {(x'-^) 8 + (y-i/) 2 + (^- ^ ) 2 }* , 



r _ rrr gxd1>drid$ 



u -J J J {(£ - *)« + (, -yf + « - *) 2 }4' 

 <j> = /yy gq'dx'dy'dz* 



././■/ {(^' - if + (y - >j) 2 + j? - 6"ji* 



r = /7 T yvyd^d^d^ 



7 JJJ { (*r " *)* + <h ~ ")* * (?r ~ OT* 

 (y subscript refers to the 5th molecule). 



These integrals being taken between suitable limits, we have 

 for the equilibrium of the aether the equations 



di 



_ _ dF ^dG ^ 

 dx dx dx 



dy dy dy 



Slip _ iE + xi^ 



dz dz dz 



H 



(1.) 



(2.) 



and for that of the centre of gravity of a molecule, 



In both these systems of equations X refers to the various 

 molecules whose equilibrium we are considering; in (1.) it 

 extends to all the molecules ; in (2.) to all but one. 



The double integrals in (2.) are to be extended to the whole 

 surface of the molecule under consideration, and the triple 

 integrals to its whole volume. Such are M. Mossotti's equa- 

 tions. Let us begin by examining the meaning of the several 

 terms of those of the second system. The last terms of these 



Phil. Mag. S. 3. Vol. 19. No. 125. Nov. 1841. 2 C 



