fic> EFFECTS OF ELECTRICIXV AKD HEAT, 



indantaneoiis, it would only have experienced a progrelTive 

 diminution by cooling, as when its expanfion is owing to 

 heat. 

 When ammoni- In the experiment by which ammoniacal gas is deconipofed, 

 '*^*! ^7 H^ b*^' ^^^ S^^ indubitably receives the eledric a6lion, and neverthe- 

 eleftiicity, itrc-lefs it is not heated ; and as foon as the decompofition isfinidi- 

 nuins colJ. gj^ j^j volume remains unchanged, becaufe the eledric a6lion 

 whicli is employed in this experiment, is not Sufficiently ener- 

 getic to caufe a perceptible dilatation. No fenfible dilatation 

 is produced in a gas by a fhock which is not very ftrong, be- 

 caufe the impulfe not being gradual, like the expanfion arifing 

 from caloric, and being excited inltantaneoufly, the refiftance 

 of the liquid becomes too great, and cannot be overcome un- 

 lefs the dilatation has great energy. 

 LrsJ exploded In An experiment of Dieman and his learned aflbciates confirms 

 Siic,"and U ^'"' explanation : They caufed a Qiock to pals through lead 

 not fwfed. placed in a veflel filled with azote gas, which could not oxi- 



date it ; it was reduced into powder retaining all its metallic 

 properties : If it had experienced a liquefaction fimilar to the 

 adlion of heat, it would have cooled gradually, and would 

 have congealed into one, or at leafl into feveral malTes. 

 No heat is pro- When a metal is fubmilted to the eledric aftion, the effeds 

 euSric dilau- pr^^'ut-ed immediately by the eledricity muft be diftinguifned 

 tion of metals: from thofe which are owing to its oxidation: The firfl are 

 the ignition and limited to the diminution or defirudion of the efFeds of the 

 oxidation or force of cohcfion, to removing and difperfing the moleculae ; 

 combuftion. (jf by this a little heat is difengaged, it is only owing to the 

 compreffion fufiained by fome of the parts); but thofe which 

 are occafioned by the oxidation, produce a high degree of 

 heat, and then the effeds afTume all the appearances of an or- 

 dinary combullion ; hence it arifes that the mod oxidable me- 

 tals are thofe which become red with the greateft facility, and 

 wliicii moll lliew the properties of a metal liquefied by heat. 

 E'rariti y fa- Elcdricity favours (his oxidation, in as much as it diminiflies 

 vours oxidation ji,^. f^^^^^ ,,f cohcfion: it is thus that an alkali renders the 



by diminifli.ng ... 



coliuiion. action of (ulphur on oxigen much more powerful, by defiroy- 



ing the force of cohcfion oppofed to il, and that a metal dif- 

 folved in an amalgam is oxided much more eafily than when 

 it is in a folid ftate. It is only by dettroying (he effeds of 

 t].)e force of cohefion (hat heat ilfelf produces tlie oxidation of 

 inelals, but the expaufive adion of eledricity will have a great 



advaijtage 



