404 



WELLS'S NATURAL PniLOSOPHT. 



Tho first attempt to increase FiG. 334. 



^ilo ofXl/^^ t^io Po^cr of a galvanic circuit 

 by increasing tlio number of 

 the combinations, was made by Volta. He 

 constructed a pile of zinc and copper plates 

 with a moistened cloth interposed between 

 -each. He commenced with a zinc plate, upon 

 which he placed a copper plate of the same 

 ■ize, and on that a circular piece of cloth pre- 

 Tiously soatked in water slightly acidulated. 

 On the cloth was laid another plate of zinc, 

 then copper, and again cloth, and so on in suc- 

 cession, until a pile of fifty series of alternate 

 metal plates and moistened cloths was formed, 

 the terminal plate of the series at one end being 

 copper and at the other end zinc. A metallic 

 wire attached to the highest copper plate will 

 constitute the positive pole, and another to the lowest zinc plate the negative 

 pole of such a seriea 



Fig. 334 represents Yolta's arrangement of metal plates and wet cloths, 

 with the metallic wires, which constitute the poles. 



Such combinations are denominated Voltaic Piles, or 

 Voltaic Batteries, and very often Galvanic Batteries. 



As two different metals and an interposing liquid are generally employee^ 

 for this purpose, it has been usual to call these combinations pairs ov elements; 

 BO that the battery is said to consist of so many pairs or elements, each pair 

 or element consisting of two metals and a liquid. 



776. Voltaic piles or batteries have 

 been composed and constructed in 

 a great variety of forms, by combin- 

 ing together in a series various sub- 

 stances which excite electricity when 

 acted upon chemically. 



Thus, they have been constructed entirely of veg- 

 etable substances, without resorting to the use of 

 any metal, by placing discs of beet-root and walnut- 

 wood in contact. With such a pile, and a leaf of 

 grass as a conductor, convulsions in the muscles of a 

 dead frog are said to have been produced. Otlier 

 experimentalists have formed voltaic piles wholly 

 of animal substances. 



A perfectly dry voltaic pile, known 

 Describe Zam- - ... ^ „ , ., ^., 



boui'sPiie. fi-'om its mventor as Zambonis Pile, 



may be formed of sheets of gilded 



paper and sheet zinc. If several thousands oi these 



Of what sub- 

 stances have 

 Toltaic piles 

 been construct- 

 ed r 



Fig. 335. 



