Dr. Hart's Calorimotor and Dejiagraior. 365 



leaving no doubt upon the mind of either of us who witness- 

 ed for tlie first time the operation of this new machine, that 

 the charcoal was not on\y fused but volatilized ; at least the 

 piece that was connected with t!ie negative pole of the bat- 

 tery. No sooner had the ignition completely taken effect 

 than it was discovered on stopping the action, that instead 

 of a point oh the end of the negative charcoal, a cavity or 

 crater of considerable extent had been formed, the edges of 

 which were pointed or jagged. The piece attached to the 

 positive pole on the contrary was increased lengthwise by a 

 cylindrical protuberance, which, when the operation was 

 protracted, grew thicker at the extremity, acquiring an ir- 

 regular knob, the surface of which was compact, smooth 

 and glossy, resembling not a little in appearance, the sur- 

 face of hematitic iron ore. The extent of this projection 

 corresponded with the depth of the cavity in the other 

 piece, so as to leave no room for doubt that the thoroughly 

 ignited matter of the negative piece had been transferred by 

 the power of the electro-calorific current to the positive 

 charcoal ; and the appearance of the surface, especially 

 when viewed with a magnifier, indicated the fusion of the 

 transferred port(on. There was, it is true, no direct evi- 

 dence of liquifaction; and it is, I cowc&xve, possible that the 

 carbonaceous matter may have been volatilized, and again 

 condensed, without that intermediate change, as in the case 

 of many other solid substances by heat. But, however that 

 may be, the phenomenon, as it respects the charcoal, is dif- 

 ferent from any thing that has heretofore been published, 

 and it furnishes an additional and striking instance of the 

 power of the voltaic current, and of the superior efficacy 

 and convenience of Dr. Hare's instruments. The entire ab- 

 sence of insulation between the adjacent pair of plates, and 

 the great facility with which their immersions and emer- 

 sions can be effected, will doubtless give this ingenious mod- 

 ification of the galvanic apparatus a decided superiority over 

 every other. The fluid employed in the experiments ahove 

 mentioned, had, I think you informed me, remained in the 

 troughs several weeks or months. The new defllagraior, 

 described by Dr. Hare in the last No. of the Journal, which 

 I had an opportunity of seeing at the college in Providence, 

 is still more convenient. In that, the plates remain fixed, 



