Chap. 2.] Its Analogy with Heat and Light. 309 



their properties fo liberally, has in no cafe eftablifhed 

 two caufes for one effect. We may apply this remark 

 to the electric matter ; and the more we inquire into 

 the properties of the electric matter, and thofe of the 

 matter of heat and light, the more mall we difcover of 

 this analogy between them, and the more probable will 

 it appear, that fire, light, and electricity depend upon 

 the fame principle, and that they are only three dif- 

 ferent effects from the fame matter or efTence. 



i ft. Of all the means neceffary to excite the matter 

 of heat, there is none more efficacious than that which 

 is moft neceflary to produce electricity, namely, fric- 

 tion, adly. As fire, or caloric, extends itfelf with 

 more facility in metals and humid bodies than in any 

 other fpecies of bodies, fo metals and water are con- 

 ductors of electricity in the fame manner as they are 

 of heat, and, in general, the fame conductors are found 

 equally good for both. jdly. Fire, or caloric, is the 

 moft elaftic of all bodies, and is confidered by moft 

 philofophers as the principal caufe of that repulfion 

 which takes place between the particles of bodies, of 

 which the ftrongeft inltance has already been given in 

 explaining the caufe of fluidity; and to a fimilar caufe 

 the electric repulfion may be referred. 4thly. The 

 pulfe and perfpiration of animals are increafed by elec- 

 tricity as by the actual application of heat, and the 

 growth of vegetables is promoted by it *. fthly. Ac- 

 tual ignition is produced by the electric fluid : thus it 

 is a common experiment to fire fpirit of wine by the 

 electric fpark; inflammable air is fet on fire by the 

 fame means in the commc-'i electrical piftol .; and even 

 gunpowder may be exploded by a fpark from a power- 

 ful conductor. 6thly. Metals are melted by electri- 



* Count Rumford's experiments, Phil: Tranf. vol. IxxvL 



X city, 



