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XXIX. An experimental examination of the electric and chemical theories of 
galvanism. By William Ritchie, A.M. F.R.S., Rector of the Royal 
Academy at Tain. 
Read May 7, 1829. j 
i. The continental philosophers still continue to adopt the electric theory of 
galvanism proposed by Volta, whilst those in Britain as uniformly follow some 
modification of the chemical theory proposed by Dr. Wollaston. From this 
diversity of opinion we may safely conclude, that the experimental proofs for 
the truth of either theory are not sufficiently powerful, to command the assent 
of all capable of appreciating the weight of such evidence. I have therefore 
ventured to lay before the Society the following experiments and observations ; 
as they appear to me to establish the truth of some modification of the chemical 
theory, and to demonstrate the fallacy of the principles on which the electric 
theory rests. 
2. The fundamental principle assumed by Volta, and supported by his fol- 
lowers, is, that if dissimilar metals be brought into contact they are instantly 
thrown into opposite electric states. This he conceives to be a new law of 
nature, and claims to himself the honour of the discovery. He conceives that 
its truth is proved by the following experiment. 
Let Z be a plate of zinc, and C a plate of copper, soldered together 
at the line of contact A B. Hold the plate of zinc in the hand, and 
touch the under plate of a delicate electric condenser (le conden- 
sateur a lames d’or) with the copper plate, whilst a moistened finger 
is applied to the upper plate of the instrument. Remove the compound plate 
and the moistened finger, and then lift the upper plate of the instrument by its 
insulating handle, and the slips of gold leaf will be found to diverge. Taking 
for granted the truth of the experiment, the conclusion which Volta deduced 
from it by no means follows as a legitimate inference. Dr. Wollaston has 
shown that a galvanic effect is produced by dissimilar metals with the moist 
3 A 
B 
MDCCCXXIX. 
