Intelligence and Miscellaneous Articles, 389 



Nickel gave several rather feeble bands or groups of lines ; 

 whilst iron, in our experiments, gave no band sufficiently intense 

 to examine. 



The results, indicated above, show how rich the field of research 

 is which the phenomena of phosphorescence open up in the in- 

 visible part of the infra-red of the spectrum, and which, alone, 

 covers an interval of wave-lengths greater than the visible and 

 ultra-violet parts together. 



Besides the interest it may excite by proving the existence of 

 these rays, of which the wave-lengths are considerable, in the 

 spectra of metallic vapours, this research, more than any other, is 

 of the kind to give most valuable information concerning the un- 

 known laws which govern the vibratory motion of incandescent 

 vapours. — Comptes Benclus, August 25, 1884. 



CHANGE IN THE PHYSICAL PROPERTIES OF BISMUTH WHEN 

 PLACED IN A MAGNETIC FIELD. BY M. HURION. 



Eecent experiments of M. Ledru (Journal de Physique, 2 e serie, 

 vol. iii. p. 133), which may be easily repeated, show that if a plate 

 of bismuth is placed in a magnetic field and at right angles to the 

 lines of magnetic force, the equip otential surfaces of a current 

 traversing the plate are deflected from their proper direction, from 

 which it follows that the physical constitution of the metal is 

 altered. This alteration may be revealed by other effects, especially 

 by the action of polarized light. 



Dr. Kerr's researches (Phil. Mag. May 1877) have shown that a 

 mirror placed between the poles of an electromagnet rotates the 

 plane of polarization of an incident perpendicular ray through a 

 certain angle when the electromagnet is excited ; the rotation is in 

 the opposite direction of the current which produces the magneti- 

 zation. Bismuth has similar properties, as follows from the 

 following experiments. 



A mirror is prepared whose reflecting surface is produced by 

 running out the melted metal on a plate of glass heated, as done 

 by M. Bighi (Journal de Physique, 2 e serie, vol. iii. p. 127) ; the 

 glass plate with a thin layer of metal is placed between the poles 

 of a Faraday's electromagnet. The armatures of the electromagnet 

 have a perforation in the centre ; one of them is flat and the other 

 conical, and the light comes through the aperture in the latter. 

 The ray reflected at right angles returns in its original direction, 

 and meets under an angle of 45° an uncoated glass which allows 

 the direct light to pass, and directs the reflected ray sideways. 

 The incident light traverses the polarizing system of a Laurent's 

 saccharimeter, and the reflected light is received in an analyzer of 

 the same material. The electromagnet may be traversed first in 

 one direction and then in another by the current of a Gramme 

 machine of the workshop type. 



It is observed that the plane of polarization of the reflected ray 

 is deflected by about 30' when the direction of the current is 

 reversed ; the rotation is in the same direction as the current which 



