1821.] Dr. Hare's new Galvanic Apparatus, Theory, S)C. 339 



mentioned are easily fused or deflagrated by smaller pairs, 

 which would have no perceptible influence on masses that 

 might be sensibly ignited by larger pairs. These characteristics 

 were fully demonstrated, not only by my own apparatus, but by 

 those constructed by Messrs. Wetherill and Peale, and which 

 were larger, but less capable of exciting intense ignition. Mr. 

 Peale's apparatus contained nearly 70 square feet, Mr. Wethe- 

 rill's nearly 100, in the form of concentric boils, yet neither could 

 produce a heat above redness on the smallest wires. At my 

 suggestion, Mr. Peale separated the two surfaces in his coils into 

 four alternating, constituting two galvanic pairs into one reci- 

 pient. Iron wire was then easily burned, and platina fused by it. 

 These facts, together with the incapacity of the calorific fluid 

 extricated by the calorimeter to permeate charcoal, next to 

 metals, the best electrical conductor, must sanction tlie position 

 I assigned to it as being in the opposite extreme from the 

 columns of De Luc and Zamboni. For, as in these, the pheno- 

 mena are such as are characteristic of pure electricity, so in one 

 very large galvanic pair, they almost exclusively demonstrate the 

 agency of pure caloric. 



P. S. Since writing the above, I have endeavoured in every 

 m.ode which I could devise to ignite charcoal by electricity. 

 Exposed to the discharge of a powerful battery in pieces taper- 

 ing to a point, in a glass tube, in thin strips, and in powder, by 

 means of the glass usually employed for inflaming ether, it was 

 either uninfluenced, or merely dispersed, without the smallest 

 symptom of ignition, or even of increased warmth. Yet fulmi- 

 nating mercury was flashed by the discharge, under the same 

 circumstances as those in which the p ) wdered charcoal had been 

 subjected to it. The result, therefore, was such as might be 

 expected from a " mechanical concussion," Pointed wires were 

 covered with spermaceti, and exposed to a current from a fine 

 plate machine of 32 inches diameter ; yet no sign of fusion 

 appeared. Nor was a differential thermometer filled with ether, 

 according to Dr. Howard's sagacious plan, aflfected sensibly, 

 though the warmth of a finger applied to the bulb caused tne 

 fluid in the stem to move nearly a foot. 



I mentioned in the memoir, p. 332, that when a knob of lead 

 suspended by a filament to one of the poles of my deflagrator 

 was made to touch the other pole of the same instrument, the 

 knob was fused, the filament uninjured. I find the reverse is 

 the case, when a knob suspended by a filament is made the 

 medium of discharging an electrical battery. The filament is 

 destroyed, the knob remains unchanged. It must be evident, 

 therefore, that galvanic and electrical ignition are extremely 

 discordant in their characteristics. 



It is also mentioned in the memoir that a piece of silvere 



y2 



