284 MAJOR A. E. OKLEY ON THE INFLUENCE OF MOLECULAR 



We shall assume that this relation applies to all media. On our theory H will be 

 the sum of the applied and local fields and will be considered positive if it is in 

 the direction of the external field. Z we shall take to be negative, i.e., the negative 

 electron is always responsible for the Zeeman effect. 



In diamagnetic media, in general, H is positive, -- is negative, and therefore r is 



d\ 



negative, or clockwise looked at along the direction of H. The rotation is dextro- 

 gyric. 



In ferro-magnetic media, H is the resultant of the applied field and a very large 



reverse molecular field, so that H is very large and negative ; ^ is positive. Hence 



o\ 



again r is negative and the rotation is dextro-gyric as in diamagnetic media. 



In paramagnetic solutions, H may be positive or negative over magnetically active 

 atoms, and therefore the sign of r may be positive or negative. Hence some para- 

 magnetic solutions will be dextro- and some laevo-gyric. 



In the ferro-magnetic elements the magnitude of the rotation is remarkably high. 

 Thin films of saturated iron show a rotation of the order 260 million times that of 

 carbon bi-sulpbide subjected to an external field of one gauss. To test this we may 

 write 



Z Fc . . H . CM..,-,, r. 



Fo (saturated) = -2W . ~ ^ ' X ' g^ fo1 " 1TO11 > 



v ^ir ^cs,-H . _:S& for carbon himilnhidft 



r CS 2 (H = 1 gauss) - -7T ----- A . IB. 



where H c is the reversed molecular field, of the order 6 '5 x 10" gauss, H = 1 gauss. 

 The Zeeman coefficients Z Fe and Z CS2 we shall take to be of the same order, hence : 



JJ 



^Fe (saturated) _ _|_ 

 r CS 2 (H = 1 gauss) 



TT 



' 



ax 



For iron* 



A x 10 8 . /*. 



2570 I'Ol 



4410 1'28 



5890 (D) 1'51 



Near 



0'23 



X = 5890 x 10- 8 , a MF e/3A = + 



1480 x 

 * ' Smithsonian Physical Tables,' p. 196. 



