DlAMAGNETIC CONSTANTS OF BlSMUTH AND CALC-SPAR 191 







A = 1 sin 0\ ( A] + 1 1 A*,? + -LV/ A * 1 * ZA. A F + Y- AA # 

 - ^ 6 )/' + (- 



= 4 sn - J - 



- m* A ni AJ?) t jf + (if s AIJI _ 

 + -i |s. J /y ^j 6 ) // + (i-W- 5 - ^' ^ 8 - - 

 (7 = -^- 



Or we can write 



A = 41 sin { L>J. + L',u 3 + L" + etc. }, 

 B = U sin e \ MIL + M'ff + etc. \, 

 C = M{N+iy t n + JV'V + etc. }, 



where the values of L, M, etc., are apparent. 

 To sum up we may then write as before 



= - J a\A [(^ - *,) 2 + &,] + 5[(^ - *,) ' 2 + * s ] - C' (&, - *,) '} 



where A, B and (7 are the quantities we have found, a is the cosine of 

 the angle made by the axis of the crystal with the axis of the bar, and a' 

 is the cosine of the angle made by the same axis with a horizontal line 

 at right angles to the bar. 

 The equation 



# = 



gives equilibrium at some angle depending on a and a', and if either of 

 these is zero the angle can be either = or -J-, one of which will be 

 stable and the other unstable according as the body is para- or dia- 

 magnetic. 



For a diamagnetic crystal like bismuth with the axis at right angles 

 to the bar we can put 



n = cos = sin (/> and a = , 

 and we can write 



