456 On the Constitution of the Electric Fluid. 



Thus a wire of zinc and a wire of platinum can be made to 

 give " a violent shock which can scarcely be borne/' although they 

 will give absolutely no signs of electricity to the most delicate 

 electrometer. Can that shock then depend on electricity ? It 

 is hard to conceive a more persuasive fact in support of the 

 position already advanced, that there are other kinds of shocks, 

 or at least one other kind, beside an electric shock. Can it be 

 believed that two bits of wire can thus evolve such a powerful 

 charge of electricity as to give so tremendous a shock ; and that 

 this most feeble of all intensities, absolutely inappreciable by our 

 most delicate instruments, could be capable of such an effect, were 

 the quantity of electricity ten times what it is presumed to be, or 

 what the most exuberant imagination can conceive ? It need not 

 be reverted to that it is not quantity of electricity, unless it be 

 at a high intensity, that gives a shock ; and it is to be observed 

 that if the shock were derived from quantity alone, the two wires 

 employed by Jacobi should be adequate by themselves without the 

 coil ; and large plates in a voltaic series should be proportionately 

 more powerful than small ones, which is. not a fact. Common 

 sense would also point out that two wires which are capable of no 

 more than convulsing the limbs of a frog, must be inadequate to 

 give a violent shock to a man without some adscititious agent. 



Having procured 120 feet of copper bell-wire well covered 

 with sewing silk, I connected it with the positive prime con- 

 ductor of an electrical machine then giving sparks twelve inches 

 long. The wire was spread out round the room, and supported 

 everywhere on insulators. The cylinder being put in action, I 

 placed one hand on the negative conductor, and repeatedly made 

 and broke contact with the end of the wire ; but the electricity 

 •was reduced to the most feeble manifestations, scarcely affording 

 a spark ; and nothing in the least degree resembhng a shock 

 could be obtained, although without the wire the twelve-inch 

 spark was as much as could be well endured. I thought myself 

 entitled to a result as striking as that of Professor Henry, who, 

 with 120 feet of uncoated wire and a single pair of plates, obtained 

 a spark of maximum brilliancy, although with fifteen feet of wire 

 the spark was barely visible ; but, on the contrary, my sparks, 

 instead of being increased by a coated wire, were reduced from 

 twelve inches to almost nothing. Could the agent be the same ? 

 Another of Professor Henry's results is still more instructive. 

 With the same pair of plates and a ribbon of sheet-copper 96 

 feet long and an inch and a half wide, covered with silk and 

 coiled into a spiral, vivid sparks were produced of such size and 

 power that the snaps occasioned by them " could be distinctly 

 heard in an adjoining room." The coiled ribbon was also found 

 capable of giving a shock felt at the elbows*. 



* Scientific Memoirs, July 1837, p. 543. 



