





Scientific Intelligence. 425 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the Crystalline Polarity of Bismuth and other bodies, and 

 on its Relation to the Magnetic Form of Force ; by Dr. Faraday, 

 (Proc, Roy. Soc., Athen., No. 1103, Dec. 16.)— The author states 

 that in preparing small cylinders of bismuth by casting them in glass 

 tubes, he had often been embarrassed by the anomalous magnetic re- 

 sults which they gave, and that having determined to investigate the 

 matter closely, it ended in a reference of the effects to the crystalline 

 condition of the bismuth, which may be thus briefly stated. If bismuth 

 be crystallized in the ordinary way, and then a crystal, or a group of 

 symmetric crystals, be selected and suspended in the magnetic field 

 between horizontal poles, it immediately either points in a given direc- 

 tion or vibrates about that position, as a small magnetic needle would 

 do, and if disturbed from this position it returns to it. On resuspending 

 the crystal so that the horizontal lir>e which is transverse to the mag- 

 netic axis shall become the vertical line, the crystal then points with its 

 maximum degree of force. If it be again resuspcnded so that the line 

 parallel to the magnetic axis be rendered vertical, the crystal loses all 

 irecttve force. This line of direction therefore, which tends to place 

 itself parallel to the magnetic axis, the author calls the magne-crystallic 

 axis of the crystal. It is perpendicular, or nearly so, to the brightest 

 and most perfect of the four cleavage planes of the crystal. It is the 

 same for all crystals of bismuth. Whether this magne-crystallic axis 

 is parallel or transverse to the magnetic avs, the bismuth is in both 

 cases repelled from a single or the stronger pole ; its dia magnetic rela- 

 tions being in no way affected. If the crystal be broken up, or if it 

 be fused and resolidified, and the metal then subjected to the action of 

 the magnet, the diamagnetic phenomena remain, but the magne-crys- 

 tallic results disappear, because of the confused and opposing crystal- 

 line condition of the various parts. If an ingot of bismuth be broken 

 up and fragmentary plates selected which are crystallized uniformly 

 throughout, these also point ; the magne-crystallic axis being, as be- 

 fore, perpendicular to the chief plane of cleavage, and the external 

 form, in this respect, of no consequence. The effect takes place when 

 the crystal is surrounded by masses of bismuth, or when it is immersed 

 in water or solution of sulphate of iron, and with as much force appar- 

 ently as if nothing intervened. The position of the crystal in the mag- 

 netic field is affected by the approximation of extra magnets or of soft 

 iron ; but the author does not believe that this results from any attrac- 

 tive or repulsive force exerted on the bismuth, but only from the dis- 

 turbance of the lines of force or resultants of magnetic action, by 

 which thev acquire as it were new forms ; and, as the law of action 

 """' ' " * ves is, that the line or axis of magne-crystallic force tends 



If parallel, or as a tangent, to the magnetic curve or line 

 °f magnetic force, passing through the place where the crystal is $U* 

 uated, so the crystal changes its position with any change of direc- 



Secokd Series, Vol. VII, No. 21.— May, 1849. 54 







