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XX. An account of some experiments with a large voltaic battery. 
By J. G. Children, Esq. F. R. S. 
Read June 15, 1815. 
In 1809 I presented to the Society a short account of some 
experiments performed with a voltaic battery of unusually large 
plates, which has been honoured by publication in the Philo- 
sophical Transactions for that year. Since that period I have 
constructed another of still larger dimensions, the effects of 
which form the subject of the present communication. The 
copper and zinc plates of this apparatus are connected toge- 
ther, in the usual order, by leaden straps ; they are 6 feet 
long, by 2 feet 8 inches broad, each plate presenting 32 
square feet of surface. All the plates are attached to a strong 
wooden frame suspended by ropes and pullies, which being 
balanced by counterpoises, is easily lowered and elevated, so 
as to immerse the plates in the acid, or raise them out of it, 
at pleasure. The first trials of the power of this instrument 
were made in July 1813, in the presence of several philoso- 
phical friends, but the effects then fell very short of my expec- 
tations, arising, as I afterwards found, from a defect in the 
construction, which has been since remedied, and another 
copper plate added to each member of the series, so that 
every cell now contains one zinc and two copper plates, and 
each surface of zinc is opposed to a surface of copper. This 
was done at the suggestion of Dr. Wollaston, and has very 
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