282 
DR. RITCHIE’S EXPERIMENTAL RESEARCHES 
tive electricity is developed at the zinc end, and negative at the copper end. 
But the electricity developed in the dry pile has not one character in common 
with voltaic. It makes gold-leaves diverge ;—voltaic does not. It is most 
energetic with an imperfect conductor between the plates;—voltaic on the 
contrary increases with the conducting power of the fluid interposed. This 
elect ricity will not decompose water;—a slight development of voltaic does so, 
energetically. This pile is only in action when the poles are not connected ;— 
voltaic action does not exist unless the poles be connected. The experiment 
of Dr. Wollaston in which he decomposed water by common electricity might 
seem at variance with this reasoning. But this decomposition is totally unlike 
that produced by voltaic electricity; for, as Dr. Wollaston remarks, a mixture 
of oxygen and hydrogen rose from each of the fine metallic points, a fact which 
shows that the decomposition was produced in a manner essentially different. 
The decomposition in this experiment seems to have been effected by the me¬ 
chanical agency of the electric fluid. The fine electric dart shooting out from 
the invisible gold points may have actually cleaved a molecule of water which 
happened to be favourably situated, and thus its oxygen and hydrogen were 
disengaged at the point where the mechanical cleavage took place *. 
5. It does not appear to me at all necessary that zinc and copper should be 
thrown into opposite electric states to produce voltaic action. I shall make 
no suppositions with regard to those states, but ground my views of voltaic 
action on well established facts. Zinc has a much more powerful attraction 
for oxygen than copper; and yet copper has also a decided attraction for it, 
otherwise there could be no salts of this metal. Let us now suppose, merely 
for the sake of illustration, that a molecule of water is composed of an atom of 
oxygen united to an atom of hydrogen. In the Plate VIII. (fig. 1.) let the oxy¬ 
gen be represented by the white circle, and the hydrogen by the black. The 
zinc plate z, having a greater attraction for the oxygen than for the hydrogen, 
will turn round the molecule of water in contact with it, till its oxygen side 
be towards the zinc, and its opposite side towards the copper plate c, which is 
connected with the zinc by the wire w. The same thing will take place with 
* The same remarks apply to Mr. Barry’s experiments on decomposition by atmospheric electricity. 
Decomposition -was never effected by common electricity in which the component parts of the sub¬ 
stance were liberated at opposite poles. 
