ON ELECTROLYSIS AND ELECTRO-CHEMISTRY. 189 
Part II. 
Laws and Principles generally Accepted. 
(a.) The electro-magnetic action of the current passing through an electro- 
hyte is the sume as if the electrolyte were replaced by a metallic conductor of 
the same size and shape, and of such resistance that it could be substituted for 
the electrolyte without altering the current in the rest of the cirewit—This 
merely expresses the idea that the flow of electricity may be regarded as 
analogous to that of an incompressible fluid, even when an electrolyte 
forms part of the circuit, being either the fluid conductor of a battery cell 
or of a voltameter cell. The references quoted by Wiedemann (vol. i. 
p. 321) for this statement are: Wiedemann, ‘ Galvanismus,’ I. Aufl. 1861, 
p- 97; Schiller and Colley, Pogg. ‘ Ann.’ 155, 1875, p. 467 ; Cooke, ‘ Chem. 
News,’ 40, 1879, p. 22; ‘ Beibl.’ 3, p. 632; R. Kohlrausch, ‘Pogg. Ann.’ 
97, 1856, p. 401. 
The current may for some purposes be regarded as the flowing of 
positive electricity like an incompressible fluid round the circuit in the 
direction from anode to cathode, the quantity which crosses any section 
in unit of time measuring the current. For the body of the electrolyte, 
however, the language of the two-fluid hypothesis is considered by Von 
Helmholtz as more convenient, and it is usual to regard the current in 
the electrolyte as made up of the independent flow of equal quantities of 
positive and negative electricities in opposite directions. It will appear 
later that it is possible to form an estimate of the absolute rates at which 
the positive and negative quantities respectively flow, and that the ab- 
solute rates may be unequal; in that case the measures of the current at any 
section due to the flow in the two directions respectively will not be equal. 
But minute considerations of the disposal of the positive and negative 
electricity may lead to confusion (see Wiedemann, 2, § 1043); and 
evidently if we regard the current.as a convective discharge, by redistri- 
bution of parts, along a single line of molecules with oppositely electrified 
sides, the current at any given section between two molecules will be 
due entirely either to the motion of positive electricity in one direction 
or of negative in the other, according to the position of the section; and 
in that case the quantities of positive and negative electricity actually 
engaged will be double of those required, if one is allowed to suppose that 
-they pass each other instead of meeting each other. 
Itis not clear that we are justified in regarding the positive and negative 
electricities each as separate incompressible fluids continuous throughout 
the whole circuit, as suggested by Lodge (‘B.A. Rep.’ 1885); but this 
point may be more completely discussed in considering the theory of 
unequal migration of ions (Part III. § e). 
(b.) There are electrolytes in which conduciion of electricity from the elec- 
trode to the electrolyte, and again from the electrolyte to the electrode, is entirely 
‘convective,’ in the sense that no electricity can pass into an electrolyte or 
out of it again without causing a deposit of a certain number of con- 
stituent ions where the current enters, and of an equal number of the 
remainders of the decomposed molecules (opposite ions) where it leaves the 
electrolyte, the weight of electrolyte decomposed being proportional to 
the quantity of electricity transmitted. This is included in Faraday’s 
law, and is equivalent to saying that in certain electrolytes there is no 
