360 Magnetic Effects of Dr. Hare's Calorimotor. 



The needle on examination, was found to have become 

 magnetic; hs north pole being that end of the needle which 

 had been connected with the copper or negative side of the 

 calorimotor. It was again enclosed in the tube as before ; the 

 end which had acquired north polarity being now placed next to 

 the^mcplates. Afterths immersion ofthe instrument, the poles 

 of the needle were found to be reversed—the former south pole 

 having now acquired north polarity, and vice versa — the re- 

 sults obtained in this method of operating were always the 

 same ; the needle acquiring north polarity at the end which 

 was placed nearest the copper plates, while the spirals of 

 brass around the glass tube, passed from left to right. 

 When the direction of the spirals was changed, and the 

 brass wire wound about the glass tube from right to left; 

 then, that end of the needle which was connected with the 

 zinc plates always acquired north polarity. Being desirous 

 of ascertaining how long it was necessary the plates should 

 be immersed in order to produce these effects, a needle was 

 inclosed in the tube as in the former experiments, and the plates 

 were then immersed, and immediately withdrawn from the 

 fluid. On examination, the needle was found magnetic. 

 Another needle having been placed within the tube, the ca- 

 lorimotor waslowered until the plates had descended into the 

 fluid one quarter of an inch, when it was instantly raised. 

 Even in this instance, when the plates had descended only 

 one quarter of an inch \v\io the acid solution, and had remain- 

 ed there only one second, the needle was found to have be- 

 come powerfully magnetic, and readily took up iron filings. 

 This experiment was often repeated, and with the same results. 

 The preceding experiments lead to the conclusion, that when 

 a needle is subjected to the galvanic action in the manner 

 above described, it instantly becomes magnetic, and that end 

 of the needle which is connected with the copper or nega- 

 tive side of the calorimotor, always acquires north polarity, 

 when the turns of the spiral about the glass tube pass from 

 left to right; and that end connected with the copper plates 

 always acquires vi south polarity when the turns of the spiral 

 pass from right to left. 



From these experiments it appears that the same magnet- 

 ic effects are produced by Dr. Hare's calorimotor, as by power- 

 ful electrical batteries — although he justly considers his instru- 

 ment, as producing a great flow of caloric almost without 

 electricity. 



