/ z+ 



* - 



THE i^^Si**! 



LONDON, EDINBURGH 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



OCTOBER 1846. 



XLI. 0« ^e Magnetic Affection of Light, and on the Di- 

 stinction between the Ferromagnetic and Diamagnetic Con- 

 ditions of Matter. By Michael Faraday, F.R.S., Foreign 

 Associate of the Academy of Sciences, tyc. 

 [Continued from p. 156.] 



HAVING ascertained the great advantage which this form 

 of apparatus possessed for the examination of many 

 substances which would give no sensible results by the pro- 

 cess I formerly described, I proceeded to apply it to the cases 

 of air and some doubly refracting bodies (Experimental Re- 

 searches, 2237). For this purpose I made the faces of the 

 magnetic poles reflectors, by applying to each a polished plate 

 of steel ; and as the poles were moveable, their reflecting sur- 

 faces could be placed at any distance and in any position re- 

 quired, the substance experimented on being between them. 



Air. — I could obtain no signs of action upon the ray when 

 air was between the magnetic poles, even with the fourth, fifth 

 and sixth images. 



Rock-crystal. — The cubes of this substance formerly de- 

 scribed (Experimental Researches, 2178) were submitted to 

 examination ; but I could* detect no trace of action on the ray 

 of light when passing through them, although they were 0*75 

 of an inch in the side, and the ray was observed after passing 

 seven, and even nine times across them. The cubes were 

 examined in all directions. 



Iceland Spar. — A cube of this substance (Experimental 

 Researches, 2179) was examined in the same manner, but I 

 obtained no effect. 



Heavy glass presented the expected phasnomena easily and 

 well. 



Failing to procure any positive result in these trials, either 

 with air or with doubly refracting crystals, I silvered the latter 



Phil. Mag. S. 3. Vol. 29. No. 194. Oct. 1846. S 



