284 
MAJOR A. E. OXLEY ON THE INFLUENCE OF MOLECULAR 
We shall assume that this relation applies to all media. On our theory H will he 
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 eftect. 
In diamagnetic media, in general, H is positive, ^ is negative, and therefore r is 
oX 
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. 
oX 
Hence 
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 Imvo-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-sulphide subjected to an external field of one gauss. To test this we may 
write 
^ Fe (saturated) 
— _O 
77 
^Fe 
H 
X 
iron. 
^ CSa (H = 1 gauss) 
— 277 . . X . " for carbon bisulphide. 
c ax ^ 
where H^ is the reversed molecular field, of the order — G'5x 10® gauss, H = 1 gauss. 
The Zeeman coefficients Z^g and Zcs., we shall take to be of the same order, hence :— 
A'* 
' Fe (saturated) 
^ CSa (H = 1 gauss) 
For iron* 
X X 101 
2570 
4410 
5890 (D) 
Near 
pr ^/^Fe 
+ .(2) 
jX. 
rot 
1-28 
1-51 
X = 5890 X 10-®, —- 
’ 1480x 10-® 
* ‘ Smithsonian Physical Tables,’ p. 196. 
