galvanifm. 



IY4. ' -* ON GALVANISM. 



General eftefts If we CKamlne Mr. Lavoifier*s theory of combuftionj we 

 T,Vir,Z^ °^ ^^^'^ ^"^ th^^ '' depends upon the aflumption of a principle 

 whofe exiftence has never been proved by diredl experiment. 

 It is the union of the bafis of oxygen gas with thecombuftible 

 body which in every inftance is the caufe of the combuftion. 

 We have feen that this gas is produced by pofitive eleftricity 

 and water, and we conclude that the ponderable part of this 

 gas is water, becaufe we can perceive the agency of no other 

 principle or fubftance. The fimple condenfation of oxygen 

 gas, according to Mr. Lavoifier, occations the evolution of heat 

 and light. But little heat is excited by the mechanical conden- 

 fation of this gas; but we find that when a chemical union 

 takes place between a combuftible and the gas, a great portion 

 of heat and light is difengaged. 



The accenfion of charcoal and metallic bodies by the gal- 

 vanic battery, even in vacuo, feems to (hew that the eleflri- 

 cities thus produced are the peculiar agents in the phenomena 

 of combuftion. They feem not only to be the exciters of com- 

 buftion, but they furnilh with water thofe gafesby which com- 

 buftion has been conceived to be upheld. 



The theory of the Lavoifierian fchool, of the combuftion of 

 hydrogen gas, in conjun6iion with oxygen gas, is as follows : 

 " When both gafes are mixed at a lower temperature than that 

 of ignition or red heat, the attra6tion of their refpeftive bafes 

 to the caloric is, in that cafe, ftronger than their attraflion to 

 f-ach other, and therefore they are not decompofed. But in 

 the heat of ignition, their bafes, namely concrete oxygen and 

 liydrogen, again attract each other more ftrongly, and hence 

 they unite to produce water; and both the calorie and light 

 by which they are retained in their aerial form, are again dif- 

 engaged from them, and conftitute the fire." 



Now where is the evidence of the heat and light being ne- 

 ceOTary to the formation of thefe gafes, when they are produced 

 from the wires connected with the extremities of thepile, and 

 placed in water? Alfo during the oxidation of a metal in the 

 moift way, the hydrogen difcharged is at firfl: very hot, fo as 

 to heat immoderately the tubes ufed in coUeding it. If the 

 condenfation of oxygen gas be the caufe of the produdion of 

 heat and light, how comes it tl)at charcoal and nitre deflagrate 

 together with the produdion of fo much light and heat, although 

 the compound formed, namely, carbonic acid gas, occupies fo 



much 



