Capacity of Electrolytes. 345 



uniform electrical field in different liquids. The experiments 

 were undertaken with a view of verifying the results of 

 previous work, which indicated that water and alcohol possess 

 genuine specific inductive capacities much larger than most 

 other liquids, although not infinite as sometimes stated. 

 The energy of an electrical system is 



W=ljjjKH^. 



8tt 



Supposing the media isotropic, and the system to consist of a 

 solid dielectric immersed in a fluid, we may write 



W-ljffHMn+gfiJft,^, 



8tt jjj 8tt' 



where the first integral is to be taken throughout the fluid 

 and the second throughout the solid. If K : > K the force in 

 the fluid near the solid is increased, while within the solid it 

 is decreased, as compared with the forces in the absence of 

 the solid. The total energy is, however, increased by the 

 presence of the solid, and if the field is variable the solid is 

 acted upon by a resultant force which urges it toward the 

 stronger parts of the field.. If, however, K X <K the solid 

 tends to move toward those regions where the electric force 

 is less. This is analogous to the case of magnetic and 

 diamagnetic bodies in a magnetic field. 



These considerations lead one to expect that glass (for 

 example) would go toward the stronger parts of the field in 

 air, turpentine, and other dielectrics having a small value of 

 K, and toward the weaker regions of the field in water and 

 alcohol. Moreover, since K for water and alcohol is very- 

 large, the glass would experience a force many times greater 

 in water in the one direction than in air in the other. These 

 anticipations have been completely realized. 



The Electrical Field, 



II. In order to obtain an electrical field in which the in- 

 tensity of the electric force varies in a known manner, I chose 

 the case of two parallel wires oppositely charged. As is well 

 known, the equipotential surfaces and tubes of force are in 

 this case circular cylinders intersecting orthogonally. A 

 section perpendicular to the two parallel wires M, N is shown 

 in fig. 1, Plate IX. The field may be calculated by means of 

 conjugate functions in two dimensions. Putting 



log {x + iy) = ct + i/3 



