[ H6 j 



XIII. Oil the Tliermo- Magnetism of Homogeneous Bodies ,- w//// 

 illustrative Expc7-imctits. By Mr. Wm. Sturgeon, Lecturer 

 on Experimental Philosophy at the Hon. East India Companies 

 Military Academy^ Adiscombe. 



[Concluded from page 24.] 



Sixth Class of Expoiments. 

 88. Experiments laith irregular Masses of Antimony. 



'T'HE object of these experiments was that of ascertaining 

 ■*■ if the same laws of thermo-magnetic action, as regards 

 the crystalline arrangement of the metal and point of heat, as 

 those which were developed in the experiments with cylinders 

 and cones of antimony could be traced in masses of an irre- 

 gular figure, by making the point of heat in various parts of 

 those fine smooth extensive faces of crystalline laminae which 

 are to be met with only in fractures of large masses which 

 have been very gradually cooled from fusion. 



89. The experiments were made by heating, separately, 

 particular points in those lamellated faces, and then tracing 

 the direction of the electric currents by expeditiously apply- 

 ing the antimony to a magnetic needle, and noting minutely 

 the character of the deflection ; and it appears, from the uni- 

 formity of the results of a considerable number of experi- 

 ments on various pieces, that the thermo-magnetic phseno- 

 mena elicited in irregular masses have precisely the same re- 

 lation to the position of the metallic films and point of heat 

 as those displayed by cylinders and other regular forms of 

 antimony. 



90. It will not be necessary to enter into a detailed account 

 of the several experiments which were instituted for this in- 

 quiry, as a description of those which were made on one of 

 the irregular pieces, and of the resulting phsenomena, will be 

 sufficient to illustrate the whole. And I have every reason to 

 believe, that the same laws which govei'n these phtenomena, 

 will be found to appertain to all similar crystalline arrange- 

 ments of antimony; that they will uniformly be developed 

 under similar circumstances, and consequently that they are 

 intimately related to the crystallization of the metal. 



91. The piece of antimony on which these experiments 

 were made, weighed about three pounds ; it was separated by 

 the blow of a hammer from a large mass, and the frac- 

 ture exposed a smooth triangular face of parallel crystalline 

 plates, without presenting any intersecting edges of metallic 

 laminae whatever. This triangular face will be represented 

 by figs. 16, 17, 18; and the arrows in those figures will show 



the 



