1821.] Dr, Hare* s new Galvanic Apparatus, Theory, ^c. 337 



three-sixteenths of an inch asunder ; so that the circulation may 

 go on more rapidly. 



Pursuant to the doctrine, which supposes the same quantity 

 of electricity, varying in intensity in the ratio of the number of 

 pairs to the quantity of surface, to be the sole agent in galvanic 

 ignition, the electrical fluid as evolved by Sir H. Davy's great 

 pile must have been nearly two thousand times more intense 

 than as evolved by a single pair, yet it gave sparks at fio greater 

 distance than the thirtieth or fortieth of an inch. The intensity 

 of the fluid must be at least as much greater in one instance 

 than in another, as the sparks produced by it are longer. A fine 

 electrical plate machine, of 32 inches diameter, will give sparks 

 at 10 inches. Of course the intensity of the fluid which it emits 

 must be 300 times greater than that emitted by 2000 pairs. 

 The intensity produced by a single pair must be 2000 times less 

 than that produced by the great pile ; and, of course, 600,000 

 times less than that produced by a good electrical plate of 32 

 inches. Yet a single pair, of about a square foot in area, will 

 certainly deflagrate more wire than a like extent of coated sur- 

 face charged by such a plate. According to Singer, it requires 

 about 160 square inches of coated glass, to destroy watch pen- 

 dulum wire ; a larger wire may be burned off by a galvanic 

 battery of a foot square. But agreeably to the hypothesis in 

 dispute, it compensates by quantity for the want of intensity. 

 Hence the quantity of fluid in the pair is 600,000 times greater, 

 while its intensity is 600,000 times less ; and vice versa of the 

 coated surface. Is not this absurd ? What does intensity mean 

 as applied to a fluid? Is it not expressed by the ratio of quantity ' 

 to space? If there be twice as much electricity within one cubic 

 inch, as within another, is there not twice the intensity? But » 

 the one acts suddenly, it may be said ; the other slowly. But 

 whence this difference ? They may both have exactly the same 

 surfiace to exist in. The same zinc and copper plates may be 

 used for coatings first, and a galvanic pair afterwards. Let it 

 be said, as it may in truth, that the charge is, in the one case^ 

 attached to the glass superficies ; in the other, exists in the pores 

 of the metal. But why does it avoid these pores in one case, 

 and reside in them in the other? What else resides in the pores 

 of the metal which may be forced out by percussion? Is it not 

 caloric? Possibly, unless under constraint, or circumstances 

 favourable to a union between this principle and electricity, the 

 latter cannot enter the metallic pores beyond a certain degree of 

 saturation ; and hence an electrical charge does not reside in the 

 metallic coatings of a Leyden phial, though it fuses the wirev 

 which forms a circuit between them. 



It is admitted that the action of the galvanic fluid is upon, or 

 between, atoms ; while mechanical electricity, when uncoerced, 

 acts only upon masses. This difference has not been explained 

 unless by my hypothesis, in which caloric, of which the influence 



New; Series, vol. i. y 



