178 
PHYSICS: S. J. BARNETT 
THE MAGNETIZATION OF IRON, NICKEL. AND COBALT BY ROTA. 
TION AND THE NATURE OF THE MAGNETIC MOLECULE 
By S. J. Barnett 
DEPARTMENT OF PHYSICS. OHIO STATE UNIVERSITY 
Communicated by R. A. Millikan, January 15, 1917 
In December, 1914, I described to the American Physical Society 
an extended series of experiments made in that year on the magneti- 
zation of large steel rods by mere rotation. ^ 
Before these experiments were made only one method of magnetizing 
a body was known, viz., placing it in a magnetic field. These experi- 
ments not only revealed another and entirely new method, but they 
also confirmed completely the fundamental assumptions on which the 
results had been predicted: They proved, in a direct and conclusive 
way, on the basis of classical dynamics alone, without dependence upon 
the theory of radiation, (1) that Ampereian currents, or molecular cur- 
rents of electricity in orbital revolution, exist in iron; (2) that all or 
most of the electricity in orbital revolution is negative; and (3) that it 
has mass or inertia, so that each orbit behaves like a minute gyrostat 
and tends to set itself with the direction of revolution coincident with 
the direction of rotation of the body. It is in this way that magnetiza- 
tion of the body results. Furthermore, if we admit the classical theory 
of radiation, these experiments, together with the existence of residual 
or permanent magnetization, prove (4) that the arrangement of the 
electricity in the Ampereian orbits is Saturnian rather than planetary. 
If it is assumed that only one kind of electricity is in orbital revolu- 
tion, and if the mass of a particle is denoted by m and its charge by 
theory shows that the rotation of a body with angular velocity n revo- 
lutions per second is equivalent to putting it in a magnetic field of in- 
tensity H, such that 
E/n = 4:Tm/e. (1) 
If we assume that electrons alone are in orbital revolution, the value 
of the second member of this equation is —7.1 X 10~^ e. m. u. accord- 
ing to well known experiments on electrons in slow motion, and H/n 
should be equal to this quantity and identical for all substances. If 
positive electricity also participates, the magnitude of H/n should be 
smaller. The value of H/n in my 1914 experiments was —3.6 X 10~'^ 
e.m.u. 
A little later, in February and April, 1915, Einstein and de Haas^ 
described to the German Physical Society successful experiments on 
