220 Mr. J. R. Ashworth. Methods of making Magnets 



coefficients for three and two pieces bound together, the third point 

 that for a single piece, and succeeding points the coefficients for the 

 same piece at three stages of dissolution. The third curve is con- 

 structed from the data in Table V, and represents the passage from 

 a positive to a negative coefficient in No. 34 wire. 



Diagram II exhibits the curve of permanent loss, /3, and dimension 

 ratio, R, taken from Table VI for No. 30 wire, diameter constant,, 

 and it will be seen it follows remarkably closely the path of the co- 

 efficient curve. The coefficient, a, and the permanent loss, /3, may 

 then be connected by a linear equation 



a = a+b/3. 



The values of the constants for this material are 



a = — 0-0005228 + 0-0000073 and 

 b = +0-001886 + 0-000043. 



If curves for a and /3 be plotted with demagnetising factors, i.e., 

 the demagnetising force per unit intensity, corresponding to their 

 dimension ratios as abscissas they resemble, strikingly, curves of 

 magnetisation, having a point of inflection near the beginning and 

 ultimately approaching horizontal asymptotes (Diagram III) ; by 

 prolonging the curves in this diagram until they cut the axis of 



