452 Mr. M. Donovan on the supposed Identity of the Agent 



cumstances of the chemical action now taking place, the result 

 of which I conceive to be an alteration in the constitution of that 

 agent. The cause or manner of this alteration I am no more 

 able to assign than the supporters of the common hypothesis are 

 to explain the difference between tension and current by the 

 agency of quantity. The difference of properties between common 

 and voltaic electricity is nevertheless so obvious, to all appearance, 

 that it was formerly attributed to the operation of a distinct gal- 

 vanic fluid or influence. 



According to these views, the phenomena of the charged 

 Leyden battery become perhaps a little more intelligible. When 

 the connexion of the poles of the voltaic series is made with the 

 coatings of the Leyden battery, the circuit still remains open, 

 just as it did before the connexion. Ordinary electricity only is 

 generated, as in the experiment of Lavoisier and La Place, and 

 it gives a weak charge to the Leyden battery. This battery will 

 accordingly give a common electric shock or spark, both of a very 

 feeble kind, even although the battery be very large and the vol- 

 taic series extensive ; but when the Leyden batteiy is removed, 

 and the connexion between the two poles of the voltaic series is 

 effected by the application of a wet hand to each, the circuit is 

 at that moment closed by a good conductor ; the true chemico- 

 voltaic action of the exciting liquid therefore instantly takes place ; 

 the electric fluid, now altered by a change in the ratio of its con- 

 stituent elements, is evolved, and a violent shock is received which 

 is continued as long as the contact subsists. The moment the 

 hands are removed, the true chemico-voltaic action ceases ; the 

 chemical action that succeeds is of the ordinary kind, and common 

 electricity is evolved as at first. 



This immediate charge of a Leyden battery is the circumstance 

 from which the enormous quantity of electricity, affirmed to be 

 generated by a voltaic series, derives its chief support. It is an 

 interesting phsenomenon; but if the foregoing reasonings be 

 well-founded, the inquiry into that part of the subject is foreign 

 to the question relative to the alleged identity, the real one being, 

 not whether much electricity rapidly enters the Leyden battery, 

 but whether that electricity is the cause of the phenomena which 

 a voltaic series, not the Leyden battery, presents. If the shock 

 given by the Leyden battery, charged by the voltaic series, be 

 merely the effect of ordinary electricity, and not the same as the 

 shock given by the series itself, it were beside our purpose to 

 make any inquiries about it. 



How the defenders of the electrical hypothesis of galvanism 

 can acknowledge that the Leyden battery is charged with elec- 

 tricity from an unclosed circuit, and assume the fact as corrobo- 

 rative of their views, seems unaccountable, when they at the same 



