472 Intelligence and Miscellaneous Articles. 



Messrs. Wheatsone, Joule, Wertheim, and De la Rive, showed in 

 various ways the influence of magnetization on the molecular con- 

 stitution of iron and of steel. 



The vibrations produced in rods and wires of steel or of soft iron 

 by an alternate succession of magnetizations and demagnetizations, 

 as well as the modifications which magnetization produces in the 

 elasticity and even the dimensions of these metals, have led to the 

 assumption that the development of magnetism is due to a common 

 direction imparted to the particles of magnetic metals, and conse- 

 quently to a change in the arrangement of the molecules — a conclu- 

 sion directly verified by a great number of researches, and especially 

 by those of M. Wertheim. The following new fact confirms in a 

 remarkable manner this mode of view. 



M. Treves has been led to examine the change of molecular con- 

 dition produced in a bar of iron when it is subjected to a magnetic 

 action. 



He takes two identical steel tuning-forks, which therefore are in 

 unison ; he provides them with mirrors by Lissajou's method, and 

 arranges them opposite and in planes at right angles to each other. 

 One of them is surrounded by a stout helix, through which is passed 

 the current of a battery of eight elements. If one of them be sounded 

 by a bow the vibrations commence ; and as the tuning-forks are in 

 tune, the figure reflected in the second mirror is a perfectly fixed 

 luminous circle. Magnetizing suddenly the tuning-fork in the 

 middle of the coil, the luminous circle is at once inclined, changes 

 into an ellipse, vibrates right and left with a velocity which gives 

 the measurement of the new vibratory motion. 



The tuning-forks used gave 136 simple vibrations in a second ; 

 and it has constantly been observed that a beat was produced at 

 intervals of six seconds, which means that in a second the tuning- 

 fork suddenly magnetized gave 136 t V vibrations. If the current be 

 opened (that is, the tuning-fork restored to its natural state), the 

 figure ceases to move and again becomes a fixed circle. 



Since 1847 Mr. Joule*, working with soft iron and with steel 

 wires stretched or not stretched, had observed the changes in length 

 and volume when they are magnetized. The preceding arrangement 

 may also be utilized for this investigation ; and M. Treves proposes 

 to use this optical method, as well as graphically tracing vibrations, 

 to observe these effects in steel according to their composition and 

 physical state. — Bibliothlque Universelle, September 15, 1868, 

 Comptes Rendus, August 3, 1868. 



* Philosophical Magazine, S. 3, vol. xxx. pp. /6, 225. 



