1821.] Dr. Harm's new Galvanic Apparatus, Theory , S^c. S31 



effect was perceived, until they were very near, when a vivid 

 flash was observed, and happening to touch ahiiost at the same 

 time, they were found fused and incorporated at the place of 

 contact. I next soldered to each pipe a brass cylinder of about 

 five-tenths of an inch bore. These cylinders were made to 

 receive the tapering extremities of a piece of charcoal about two 

 inches long, so as to complete the circuit. The submersion of 

 the coils caused the most vivid ignition in the coal. It was 

 instantaneously and entirely on fire. A piece of platina of about 

 a quarter of an inch diameter in connexion with one pole, was 

 instantly fused at the end on being brought in contact with some 

 mercury communicating with the other. When two cylniders 

 of charcoal, having hemispherical terminations, were fitted into 

 the brass cylinders and brought nearly into contact, a most vivid 

 ignition took place, and continued after they were removed about 

 .a half or three quarters of an inch apart, the interval rivalling the 

 sun in brilhancy. The igneous fluid appeared to proceed from 

 the positive side. The charcoal in the cylinder soldered to the 

 latter, would be intensely ignited throughout, when the piece 

 connected vv^ith the negative pole was ignited more towards the 

 extremity approaching the positive. The most intense action 

 seems to arise from placing a platina wire of about the eighth of 

 an inch diameter, in connexion with the positive pole, and 

 bringing it in contact with, and afterwards removing it a small 

 distance apart from, a piece of charcoal (fresh from the fire) 

 affixed to the other pole. 



As points are pre-eminently capable of carrying off (without 

 being injured) a current of the electrical fluid, and very ill quali- 

 fied to conduct caloric ; while, by facilitating radiation, charcoal 

 favours the separation of caloric from the electricity which does 

 not radiate ; this result seems consistent with my hypothesis, 

 that the fluid as extricated by Volta's pile is a compound of 

 caloric and electricity ; * but not v/ith the other hypothesis^ 



* According to the theory here alluded to, the galvanic fluid owes its properties to 

 caloric and electricity, the former predominating in proportion to the size of the pairs, 

 the latter in proportion to the numher, being in both cases excited by a powerful acid. 

 Hence in batteries which combine both qualifications sufficiently, as in all those mter- 

 vening between Children's large pairs of two feet eight inches by six feet, and the 2000 

 four-inch pairs of the Royal Institution, the phenomena indicate the presence of both 

 fluids. In De Luc's column, where the size of the pairs is insignificant, and the energy 

 of interposed agents feeble, we see electricity evolved without any appreciable quantity 

 of caloric. In the calorimotor where we have size only, the number being the lowest 

 possible, we are scarcely able to detect the presence of electricity. 



When the fluid contains enough electricity to give a projectile power adequate to pass 

 through a small space in the air, or through charcoal, v/hich impedes or arrests the calo- 

 xic, and favours its propensity to radiate, this principal heat is evolved. This accounts 

 for the evolution of intense heat under those circumstances which rarifies the air, so that 

 the length of the jet from one pole to the other may be extended after its commence- 

 ment. Hence the portions of the circuit nearest to tlie intervening charcoal, or heated 

 «pace, are alone injured ; and even non-conducting bodies, as quartz, introduced into it 

 are fused, and hence a very large wire may be melted by the fluid, received through a 

 small wire imperceptibly affected. 



See Silliman's Journal, No. 6, vol. i; Thomson'^' Annals, Sept. 1810; Tilloch's 

 Philosophical Magazine, Oct. 18 Jlgi^vKJiv -.„../.,',, r 



