Brown — Chrome Steel Permanent Mac/nets. 



351 



Table I. 



The annealing has had very little effect on the magnetic moment, though 

 in most cases the loss due to percussion has been greatly diminished. In 

 the paper already referred to, Mme. Curie states that small quantities of 

 silicon have little or no effect on the magnetic properties of a magnet. 

 Assuming this to be ease, if we plot from the above Table the percentage of 

 chromium as abscissae, and the corresponding magnetic moments per gramme 

 as ordinates, the resulting curve rises smoothly to a maximum at a point 

 which would represent 2-5 per cent, of chromium, then drops to the point at 

 3'5 per cent, of chromium, and goes along in a practically horizontal direction. 

 The point on the curve for magnet No. 5 is a little low, and that for No. 6 

 is rather high, which results are no doubt due to the presence of copper in 

 the one case, and of manganese and high carbon in the latter case. 



From this temporary curve it seems probable that the best effect would 

 be obtained with a magnet containing 2|- per cent, of chromium giving a 

 magnetic moment per gramme of about 54, and that a further addition of 

 chromium would reduce the magnetic moment. 



Comparing Nos. 1 and 2, which have approximately the same amount of 

 carbon, the extra manganese and chromium in No. 2 have raised its magnetic 

 moment by about 19 per cent, (in the annealed condition), and diminish ^d its 

 percentage loss about four times ; and in No. 3 the slightly less carbon and 

 manganese, and the slight increase of chromium, have raised its moment 

 about 2^ per cent. 



Comparing Nos. 1 and 7, which have practically the same amount of 

 chromium and the same magnetic moment in the annealed condition, it 



