CHAP, i.]- ELECTRICITY AND MAGNETISM. 39 



the edges of a cube to be nearly two and a half times 

 as great as the density at the middle of a face ; while 

 the density at a corner of the cube was more than four 

 times as great. 



36. Redistribution of Charge. If any portion 

 of the charge of an insulated conductor be removed, the 

 remainder of the charge will immediately redistribute 

 itself over the surface in the same manner as the original 

 charge, provided no other conductors or bodies charged 

 with electricity are near to perturb the distribution by 

 complicated effects of induction. 



If a conductor be charged with any quantity of elec- 

 tricity, and another conductor of the same size and shape 

 (but uncharged) be brought into contact with it for an 

 instant and then separated, it will be found that the 

 charge has divided itself equally between them. In the 

 same way a charge may be divided equally into three or 

 more parts by being distributed simultaneously over three 

 or more equal and similar conductors brought into contact. 



If two equal metal balls, 'suspended by silk strings, 

 charged with unequal quantities of electricity, are 

 brought for an instant into contact and then separated, 

 it will be found that the charge has redistributed itself 

 fairly, half the sum of the two charges being now the 

 charge of each. This may even be extended to the 

 case of electricities of opposite signs. Thus, suppose two 

 similar conductors to be charged one with 5 units of 

 positive electricity, and the other with 3 units of negative 

 electricity, when these are made to touch and separated, 

 each will have a positive charge of i unit ; for the 

 algebraic sum of + 5 and 3 is + 2, which, shared 

 between the two equal conductors, leaves -f i for each. 



37. Capacity of Conductors. If the conductors 

 be unequal in size, or unlike in form, the shares taken 

 by each in this redistribution will not be equal, but 

 will be proportional to the electric capacities of the 

 conductors. The definition of capacity in its relation 



