1<AWS OF GALVANISM, 2431 



but 16 =: 2'* J hence 2* = 2^— * ; therefore p = 6 ; hence 

 the force of plates are as the 6th power of their diameters. 



When the furfaces are equal, the igniting force is as the 4th 

 power of the (ides of the individual plates; for in this cafe we 

 have n zv'^ z=:my^, and n : m : : y^ : rv^ ; therefore the theo- 

 rem WW;* : my^ : : i : Zt becomes t/"^ iv^ : tp''' y^ : : I : z ; that 

 is, w^ : y^ : : I : z, which is the law in your particular cafe. 



This theorem will be found ufeful in eftiraating the force of 

 batteries in general ; as an example of which we fhall calcu- 

 late, by means of it, the force of your intended battery, con- 

 lifting of 50 plates, each 24 inches diameter. In order to de- 

 termine the quantity of wire that will be ignited by fuch a 

 battery, we have w =: 100, m = 50, w = 4, y = 24, or fix 

 times tv, / = { ; therefore 100 x 4<^ : 50 x 6^ w^ : : I : z; 



6^ 

 that is, 2 : 6^ : ; f : z, and z = --- = 36^ x 9 incites, or 



4 



972 {eet. 



I am. Dear Sir, 



Your's refpedfullj, 



THOMAS HARRISON. 



Stramongate, Kendal. 



YOU will obferve, Mr. Editor, from the above theorem. Experiments on 

 that my ftatement of the powers of two different galvanic the decompofi- 

 arrangements, equal in their metallic furfaces, being as the 

 fquares of the furface of two individual plates, or, which is 

 tlie fame, as the 4th power of the diameter of each plate, is 

 corre6t only where the metallic furfaces are equal ; when they 

 sye not equal, then the powers are as the 6th power of the 

 ' diameters, or as the cubes of their refpedtive furfaces. 

 . In a fhort time you will have the pleafure of a paper from 

 Mr. Gough, relative to the decompofition of water by gal- 

 vanifm: With this view we tried together the following ex- 

 periments, the refults of which tend to favour the explanation 

 I have attempted in the Elements I fometime fince publifhed* 



For this purpofe I employed 270 plates, contaiainga fur- 

 face of €720 fquare inches, and connected with the pofilive 

 and negative fides by wires of platinum. Thefe platinum wires 

 were inferted in a difti of water at eight inches from each 

 other; the pofitive wire difengagedpxigen gas, the negative 



R2 wire 



