with a Reply thereto by Prof. Daniell. 463 
to the anode on the left, by which each atom of sodium in the row 
will be transferred from the atom of acid with which it was pre- 
viously combined, to that next upon the right, causing an atom of 
the metal to be liberated at the cathode; this atom, deoxidizing 
water, will account for the soda and hydrogen at the cathode. 
Meanwhile the atom of sulphate on the left, which has been deprived 
of its sodium, must simultaneously have yielded to the anode the 
oxygen by which this metal was oxidized. Of course the acid is left in 
the hydrous state, usually called free, though more correctly esteemed 
‘to be that of a sulphate of water. 
«“ 74. I cannot conceive how any other result could be expected 
from the electrolysis of the base of sulphate of soda, than that which 
is here described. 
«75. JT will, in the next place, consider the phenomena observed 
by Prof. Daniell, when solutions of potassa and sulphate of copper, 
separated by a membrane, were made the medium of a voltaic current. 
«© 76. Of these I here quote his own account, Philosophical Ma- 
gazine and Journal, vol. xvii. p. 172*. 
«77. Itwill be admitted, that agreeably to the admirable re- 
searches of Faraday, there are two modes in which a voltaic current 
may be transmitted, conduction and electrolyzation. In order that it 
may pass by the last-mentioned process, there must be a row of anions 
and cathions forming a series of electrolytic atoms extending from 
the cathode to the anode. It is not necessary that these atoms should 
belong to the same fluid. A succession of atoms, whether homo- 
geneous, or of two kinds, will answer, provided either be susceptible 
of electrolyzation. Both of the liquids resorted to by Daniell, con- 
tained atoms susceptible of being electrolyzed. If his idea of the 
composition of sulphate of copper, and the part performed by the 
potassa, were admitted for the purpose of illustration, we should, on 
one side of the membrane, have a row of atoms consisting of oxy- 
sulphion and copper; on the other, of oxygen and hydrogen. 
«78. Recurring to Daniell’s own description of the electrolyzing 
process, above quoted, an atom of copper near the anode being li- 
berated from its anion, oxysulphion, and charged with electricity, 
seizes the next atom of oxysulphion, displacing and charging an 
atom of copper therewith united. The cupreous atom thus charged 
and displaced, seizes a third atom of oxysulphion, subjecting the 
copper, united with it, to the same treatment as it had itself pre- 
viously met with. This process being repeated by a succession of 
similar decompositions and recompositions, an electrified atom of 
copper is evolved at the membrane, where there is no atom of oxy- 
sulphion. Were there no other anion to receive the copper, evidently 
the electrolyzation would not have taken place; but oxygen, on the 
one side of the membrane, must succeed to the office performed by 
oxysulphion on the other side ; while hydrogen, in like manner, must 
succeed to the office of the copper. 
«79. Such being the inevitable conditions of the process, how 
* This account, having already appeared in this Journal, it is not neces- 
sary to repeat. 
