Mechanical and Galvanic Electricity. 215 



to the premises, from a state of extreme density, as when ex- 

 tricated by galvanic action from water or zinc. 



I ascertained, some years ago, that the galvanic fluid evolved 

 by a large calorimotor of a single pair, will not ignite a wire 

 which may be easily deflagrated by a much smaller apparatus 

 of the same construction. Yet sheets of metal, about four inches 

 in breadth, might be raised by a discharge from the larger 

 instrument above the temperature of boiling water. In such 

 cases, agreeably to the doctrine of quantity and intensity, the 

 electric fluid exists, up to the period of its evolution, in a state 

 of extreme condensation and consequent intensity, and yet at 

 the moment when a perfect but restricted channel is afforded 

 to it, becomes too diffuse to pass through it with a velocity suf- 

 ficient to produce deflagration. How can the electricity which 

 is in the one case so dense, become in the other so rare? 

 Where, and in what manner does it exist intermediately be- 

 tween the period of its condensation within the pores of the 

 generating materials, and its rarefaction in the wire which forms 

 the circuit between them ? 



I am aware that to the want of adequate insulation, the in- 

 ferior intensity of the charges communicated to coated surfaces 

 by voltaic apparatus, will be attributed ; as it cannot, without 

 a palpable contradiction, be ascribed to any defect of intensity, 

 in a source wherein the ratio of the quantity to the space is 

 almost infinitely great. 



Let us, then, examine the subject agreeably to this view of 

 the case. Since the electricity liberated by electro- chemical 

 reaction by means of a single galvanic pair must have pre- 

 existed in a state of extreme condensation and consequent in- 

 tensity, it follows that it ought to be productive of a tension 

 limited only by the insulating power of the menstruum within 

 which it is extricated. It should then, when evolved as above 

 described, attain the highest degree of intensity consistent with 

 the insulating power alluded to. That this is not the fact, is 

 fully established by general experience, and by the observations 

 of Faraday, according to which the intensity of a voltaic series 

 increases with the number of pairs employed. 



It results also from the premises, that the tension should be- 

 come as great in a large as in a small pair; and by employing 

 one large pair, effects should be attainable, as potent in respect 

 to intensity, and more potent as respects quantity, than those 

 resulting from a series of pairs. Yet the experiments above 

 mentioned prove, that as the surfaces, associated as a single 

 galvanic pair, are enlarged, the intensity lessens; so that a ca- 

 lorimotor of a single pair containing fifty square feet of zinc, 

 will not, in a wire of any size, produce an ignition of as high 



