184 Br. Tyndail on Diamagnetism and Magnecrystallic Actioti, 



This I repeated several times with several difFercnt crystals,, and 

 with the same unvaiying result ; the line of compression always 

 stood equatorial, and it was a matter of perfect indifference 

 whether this line was the map;necrystallic axis or not. The ex- 

 periment was then repeated with a common vice. I rubbed the 

 letters from two copper coins with sandstone, and polished the 

 surfaces ; between the plates thus obtained various pieces of bis- 

 muth were placed and squeezed forcibly together ; in this way 

 plates of bismuth were procured about as thick as a shilling, 

 and from half an inch to an inch in length. Although the dia- 

 magnetism of the substance tended strongly to cause such a 

 plate, suspended from its edge between the poles, to take up the 

 equatorial position, although the force attributed to the magne- 

 crystallic axis worked in each case in unison with the diamag- 

 netism of the mass, every plate set nevertheless with its length 

 from pole to pole, and its magnecrystallic axis equatorial. 



This superior repulsion of the line of compression manifests 

 itself upon the torsion balance also. The cubes of bismuth cry- 

 stal already made use of were squeezed in a vice to about four- 

 fifths of their former thickness ; the line of compression in each 

 case being perpendicular to the principal cleavage, and conse- 

 quently parallel to the magnecrystallic axis. From the masses 

 which were thus rendered oblong, two new cubes were formed ; 

 these, laid upon the torsion-balance in the positions indicated in 



the tables, srave the followinff results : — .*'* 



° tiij({qu uii buB 



Table XIII. — Bismuth crystals, compressed cubes. Plane of 

 most eminent cleavage parallel to axes of magnets. ,,. 



Table XIV.^ — The same cubes. Plane of most eminent cleavage 

 ' ^ perpendicular to axes of magnets. 



