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



off without increasing the intensity, it would be proper to con- 

 sider the following facts. It is a part of the voltaic hypothesis 

 that frictional electricity is the electric fluid existing in small 

 quantity at a high intensity. If a very thin wire, such as is 

 used for forming the coil of a galvanometer, be made the medium 

 of communication between the positive and negative conductors 

 of a large and powerful electric machine, it will be found on 

 turning the cylinder that a pair of pith balls, hung by wet 

 threads from the conductor, will diverge with energy. This 

 proves, that small as the quantity of electricity present is sup- 

 posed to be, the thin wire is incapable of conducting the whole 

 of it, although much does pass, and much is dissipated, as it 

 would be from any sharp- edged or pointed conductor. If, then, 

 the so-called small quantity of electricity is not freely conducted 

 by so thin a wire, how is the much (alleged) greater quantity of 

 electricity conducted which a voltaic combination is affirmed to 

 generate? It does not appear from these considerations that 

 facility of conduction can obviate the necessity of admitting in 

 the argument (what is contrary to fact), that a high intensity 

 should exist in the coil, and that enormous quantities can pass 

 through it without creating high intensity. 



The absence of all dynamic effects from a voltaic combination 

 of a single pair of large plates militates strongly with the notion 

 of the vast quantity of electricity said to be present in the cur- 

 rent which circulates between them. But it may be said, that 

 although in the case of a single pair of plates no discoverable 

 effects are manifested by the electrometer, yet when there is an 

 extensive series of plates in operation the effects are evident. 

 The truth is, that the most extensive voltaic combinations scarcely 

 exhibit greater attractions and repulsions than would be produced 

 by rubbing a stick of sealing-wax. If the power of one or two 

 thousand pairs of plates be so trivial in this respect, what must 

 be the effect of one pair ! how inadequate to account for the igni- 

 tions, fusions, combustions, and dazzling illuminations which we 

 obtain from a single large pair ! Can such phenomena be caused 

 by quantity, which being avowedly without accumulation, must 

 flow in consecutive small portions, not one of which is separately 

 effective ? yet the effect of each succeeding portion is the same 

 as that of its predecessor ; and there can be no increase of effect, 

 as there is no increase of cause. If a portion of a current could 

 pass off and leave its effects still in operation, the next portion 

 might do the same, and an accumulation of effects might be 

 imagined to subsist without an accumulation of electricity. But 

 no property of the electric fluid can remain after itself has dis- 

 appeared. A thick wire might remain red-hot for a moment 

 after voltaic current had been withdrawn ; but this would be a 



