Chap. 2.] Difference between Heat and EkRricity. 311 



bodies, and prevents them from congealing, whereas 

 congealed fluids may be highly charged with electri- 

 city i nor does it appear to have the fmalleft effect in 

 increafing their fluidity. 



3dly. Heat fpreads in every direction, whereas the 

 electrical fluid may be arrefted in its progrefs by cer- 

 tain bodies, which, on that account, have obtained the 

 name of non-conductors. The Torricellian vacuum, 

 on the contrary, affords a ready paflage to the electric 

 fluid, but is a bad conductor of heat *. 



4thly. Whenever the matter of heat penetrates bo- 

 dies, it warms as well as expands them. The electric 

 fluid does not produce thefe effects j bodies, however 

 long they may be electrified, become neither hotter to 

 the touch, nor more extended in dimenfions, 



fthly. The fmgular property of adhering to certain 

 conductors, without diffufing itfelf to others, which 

 may be even in contact with them, fo obfervable in the 

 electrical fluid, is a property not common to caloric, 

 or elementary fire. Thus we have feen that ipirits were 

 fired by an electric fpark drawn by a wire through the 

 water of the Thames, and large pieces of iron wire 

 have been heated red hot, while immerfed in water, by 

 an electrical explofion f. 



6thly. With refpect to the identity of light and 

 electricity, it fliould alfo be recollected, that light per- 

 vades glafs with the greateft facility, whereas that fub- 

 ftance is penetrated by the electrical fluid only in cer- 

 tain circumftances, and with the utmoft difficulty; if, 

 therefore, it (hould be admitted that the bafis of the 

 electric matter is radically the fame with the matter 

 of heat or light, it muft alfo be admitted, that it re- 



* Count Rumforl's experiments above quoted, 

 t Jbid, 



X tains 



