182 L. M. Cheesriian— Effect of Mechanical Hardening 



I. — Permanent Moment of Saturated Magnets. 

 The general course of the experiments here was to magnet- 

 ize to saturation wires having, as far as possible in the same set 

 of experiments, the same constitution and dimensions, bat dif- 

 fering in their hardness; then to determine their magnetic 



f>. Magnetization. — The wires were magnetized by means of a 

 large horse-shoe magnet,* and in all cases the magnetization 

 was repeated until the deflection on the magnetometer re- 

 mained constant within at least £ $. As great care was used 

 to treat all wires similarly, two magnetizations were generally 

 sufficient. 



It should be stated that a series of experiments made later, 

 the wires being magnetized by means of a coil and the current 

 from a dynamo-electric machine, afforded results differing in no 

 essential degree from those given here. 



6. Determination of the magnetic moment. — The magnetic mo- 

 ment was determined with a small magnetometer by the Gauss 

 deflection method, the magnets lying in such a position, west 

 of the magnetometer, that the prolongations of their axes were 

 perpendicular to the undeflected magnetometer needle at its 

 middle point; the readings were taken by means of a scale 

 and telescope. 



A steel mirror, [Sauerwald, diameter 22 mm ] hung on a silk 

 fiber, served as magneiometer needle. 



To eliminate any unsyrnmetrical distribution of magnetism, 

 as well as the zero point of the scale, the magnets were placed 

 alternately with their north and south ends toward the mag- 

 netometer, in both positions the scale reading being taken. 



The distance between the mirror and magnet was determined 

 within 0'15 mm , and though not always the same was about 

 450 mm ; the distance between the mirror and scale was about 

 2000™. 



7. Calculation of the Experiments. — The specific . 

 was calculated by the following formula : 



S= m =i ^.-mmi.mg-^.sec- 1 



s denoting the specific magnetism, 



m denoting the mass of the magnets in mgs., 



<p denoting half the angle of deflection of the magnet, 



T denoting the hoi aagnetism, 



r denoting the distance between the center of the magnets 



*Horse-shoe magnet made \>\ FuiK-kk-r: portative force, 50 kg. 



