Magnetic Effects of Dr. Harems Calorimotor. 359 



Upon removing the needle, its poles were found to have 

 been unaffected, the end which had been nearest the cop- 

 per, still retaining its north polarity. The same needle was 

 again submitted to the galvanic action, its north pole being 

 now placed nearest to the zinc plates of the instrument ; 

 upon examination, its poles were found to be reversed ; its 

 south pole which had been placed nearest the copper plates, 

 had acquired north polarity, while its north pole which was 

 next to the zinc plates had acquired south polarity. 



A common magnetic needle was then enclosed in the tube, its 

 south pole being placed next to the copper side of the appara- 

 tus. The plates having been immersed the usual time, the 

 needle was examined. The end which had previously been 

 its south pole, and which was placed next the copper plates, 

 had now acquired north polarity, and in every instance that 

 end of a needle which was connected with the negative 

 side of the calorimotor became its north pole, so long as 

 the spiral brass wire upon the glass tube was wound from 

 left to right. 1 then took the same glass tube and wound 

 a brass wire spirally around it, the spirals however, being 

 now wound from right to left. A needle was placed within 

 the tube, and the ends of the spirals connected with the 

 opposite poles of the calorimotor. After the immersion of 

 the plates, the needle was removed from the glass tube and 

 was found to have become magnetic — its north pole being 

 that end of the needle which had been connected with zinc 

 plates of the instrument, and vice versa. The needle was 

 then again enclosed in the tube and the plates immersed; 

 its acquired south pole being placed in connection with the 

 zinc plates. When examined, its poles were found to be 

 reversed ; its former south pole which had been connected 

 with the zinc plates having now acquired north polarity; and 

 in all cases, that end of a needle which was connected with the 

 zinc plates of the instrument, acquired north polarity, when 

 the spirals about the glass tube were wound from right to left. 



A steel needle free from magnetism, was then enclosed 

 within a tube of glass four inches long and an eighth of an 

 inch in diameter. This glass tube was then placed within 

 a tube of lead, and the lead tube again enclosed in one of 

 glass, around which was placed a spiral of brass wire, wound 

 irom'left to right; the ends of the spirals being connected with 

 the opposite galvanic poles — The plates were immersed 

 and suffered to remain in the fluid during half a minute 



