Explanation ef the Effecl of hreathing into EleB/ic Jars. 533 



a mean, it will be 20, then the increafed efFeft, gained by breathing, will be juft |, as deter- 

 mined by the wire ; and experiments 5 and 6 prove, that in order to produce fuch an increafed 

 efFeft, an addition of 4 part of the coated furface mull be added to the battery, which is about 

 816 fquare inches. This would amount to an addition of 54 fquare inches to each jar ; or, in 

 other words, if that quantity of coating could be added to each jar, the fame effeft would 

 be produced as when breathed into. But this would require the coating to be within an inch 

 of tlie top, which would render the battery unchargeable, at leaft, to that degree. A battery 

 ©f 15 jars conflruGed in tlie ufual manner, will, therefore, by this treatment, become equiva- 

 lant in power to 21 jars of the fame kind, if clean and dry. 



To explain the eifefl: of breathing into the jars, appears to be a matter of feme difficulty. 

 This experiment has been ftiewn to feveral eleftricians, and different opinions have been ad- 

 vanced, moft of which feem to imply, that breathing a<3:s as a coating to the uncoated part, 

 which will appear in the fequel to be abfurd. Mr. Nicholfon's opinion (fee Philof. Journal, 

 II. 219) comes much nearer to the truth, though it does not appear to me to be fufScient to 

 account for the efFeft produced. I admit, with hinij that a fpontaneous explofion over the 

 uncoated part is moft commonly caufed by undulation; but that this undiflation is caufed 

 by the difcharging of different charged zones, will be difficult to prove, becaufe fuch zones 

 cannot exift upon clean and dry glafs. 



When the uncoated part of a Leyden jar is made perfedly clean and dry, and the jar fct 

 to the conduftor of a machine in aftion, it will begin to charge, and, while charging, the 

 coated part of the jar, and the wire which is connected with it, become equally charged, and 

 each endeavours to throw off that furplus of eledlric fluid which is forcing into them 5 .the' 

 coating from its edges upwards, and that part of the wire which is above the coating and 

 within the jar, will endeavour to throw it in all dire£tions, which will caufe it to be furround- 

 ed by an eleftric atmofphcre, increafing in denfity as the charge increafes. This atmofphere, 

 together with that given out by the coating, fills the whole jar. Part of the eledtric fluid 

 forced Into the coating enters the furface of the glafs, but the uncoated part, being clean and 

 dry, both withinfide and without, the infide refifts the fluids entering its furface, which is 

 kept fufpended at a diftance,"becaufe the natural eleftric fluid contained on the outfide, finds 

 no means of efcape. But the aftion of the machine ftill continuing, prefTes it ftill clofer to 

 the furface, and at laft overcomes that refifting force, and fome of the particles on the outfide 

 give way, which caufes an undulation In the infide, and the eleftric fluid clofes inftantly ia 

 upon its infide furface, and forces a greater quantity from the outfide. Flafhes, or coruf- 

 cations,are thus caufed, which are always feen when a jar Is charging in the abovementioned 

 circumftances : the charge ftill continuing to be made, forces another quantity from another 

 part of the outfide of the jar, and caufes a fecond corufcatlon and undulation, which may 

 be fo ftrong as to caufe a fpontaneous difcharge ; or two or three more corufcations and 

 undulations may happen, before the difcharge, according to the fteadinefs or unfteadinefs of 

 the action of the machine, the quantity of eleftric fluid thrown ofi^ from the outfide at each 

 undulation, and alfo the degree of drynefs and cleannefs of the uncoated part of the jar. A 

 difcharge fometimes happens without having previoufly occafioned any perceptible corufca- 

 tion. This is the cafe when the firft undulation has been fo ftrong, as to caufe the whole 

 Vot. II.— March 1799. 3 Z difcharge 



