418 Harems Calorimoior. 



observes, that a wire cannot be supposed to contain an inex- 

 haustible supply of matter however subtile ; but wherefore 

 may not one kind of subtile matter be supplied to it from the 

 apparatus as well as another ; especially, when to suppose 

 such a supply is quite as inconsistent with the characteristics 

 of pure electricity, as with those of pure caloric ? 



It is evident from Mr. Children's paper in the Annals of 

 Philosophy, on the subject of his large apparatus, that the 

 ignition produced by it was ascribed to electrical excitement. 



For the purpose of ascertaining the necessity of the alter- 

 nation and proximity of the copper and zinc plates, it has 

 been mentioned that distinct square sheets were employed. 

 The experiments have since been repeated and found to suc- 

 ceed by Dr. Patterson and Mr. Lukens, by means of two con- 

 tinuous sheets, one of zinc, the other of copper, wound into 

 two concentric coils or spirals. This, though the circum- 

 stance was not known to them, was the form I had myself 

 proposed to adopt, and had suggested as convenient for a Gal- 

 vanic apparatus to several friends at the beginning of the win- 

 ter ;* though the consideration above stated induced me to 

 prefer for a first experiment a more manageable arrange- 

 ment. 



Since writing the above, I find that when, in the apparatus 

 of twenty copper and twenty zinc plates, ten copper plates on 

 one side are connected with ten zinc on the other, and a 

 communication made between the remaining twenty by a piece 

 of iron wire, about the eighth of an inch in diameter, the wire 

 enters into a vivid state of combustion on the immersion of 

 the plates. Platina wire equal to No. 18 (the largest I had at 

 hand) is rapidly fused if substituted for the iron. 



This arrangement is equivalent to a battery of two large 

 Galvanic pairs ; excepting that there is no insulation, all the 

 plates being plunged in one vessel. I have usually separated 

 the pairs by a board, extending across the frame merely. 



Indeed, when the forty plates were successively associated 

 in pairs, of copper and zinc, though suspended in a fluid held 



* Especially to Dr. T. P. Jones, and Mr. Rubens Peale, who remember the 

 suggestion. 



