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An Account of some Experiments, performed with a View to ascertain 

 the most advantageous Method of constructing a Voltaic Apparatus, 

 for the Purposes of Chemical Research. By John George Children, 

 Esq. F.R.S. Read November 24, 1808. [Phil. Trans. 18Q9,p. 32.] 



The object of the author is to determine how the greatest effect 

 may be produced by the voltaic battery, with the least waste of power 

 and expense. 



For this purpose he had one battery constructed of twenty pairs of 

 plates of zinc and copper of large dimensions, each plate being four 

 feet long and two feet wide. Each pair was connected together only 

 at the top by a strap of lead, so that both sides of each plate were 

 exposed to the action of the fluid in the trough. The trough was 

 made entirely of wood, with wooden partitions, made water-tight by 

 cement ; and this battery when in action was charged with a mix- 

 ture of three parts nitrous acid, with one of sulphuric diluted with 

 three parts of water. 



With this battery, 



1 . Eighteen inches of platina wire - v of an inch in diameter were 

 fused in about twenty seconds. 



2. Three feet of the same wire became visibly red by strong day- 

 light. 



3. Four feet of the same became very hot, but not visibly red. 



4. Charcoal burned with intense brilliancy. 



5. On iron wire, the effect was remarkably feeble. Not more than 

 ten inches of the finest harpsichord wire could be fused by it. 



6. Imperfect conductors were scarcely affected by it. No effect 

 was produced upon barytes mixed with red oxide of mercury and 

 water. 



7. A gold-leaf electrometer was not affected by it. 



8. The shock from this battery was scarcely perceptible. 



The author's second battery consisted of 200 plates, about two 

 inches square, placed in half-pint pots of common Queen's ware. 



1. With this battery potash and barytes were readily decomposed. 



2. The metallization of ammonia took place with great rapidity. 



3. It visibly ignited charcoal. 



4. It caused a strong divergence of the gold-leaf electrometer. 



5. It gave vivid sparks for upwards of three hours, and was not 

 exhausted till after forty hours. 



The results of the foregoing experiments are considered as a con- 

 firmation of Mr. Davy's observation, that intensity increases with the 

 number, and the quantity of electricity with the extent of the surface. 



The effect of quantity is seen in the first experiment on platina wire. 

 This metal not being oxidated presents no obstacle to the passage of 

 the electricities, which evolve, on their mutual annihilation, heat suf- 

 ficient to raise the temperature of the platina to the point of fusion. 



Nevertheless from want of intensity, this quantity could not find a 

 ready passage through the suboxidated iron wire, and could produce 

 no effect upon barytes or other bodies liable to be decomposed by 



