80 



Barrett, Brown & Hadfield — On the Electrical Conductivity and 



The addition of nickel does not appear to have so great an effect in lowering 

 the electric conductivity of iron as is produced by many other elements. This 

 will be seen from an inspection of the curves in fig. 4 and Plate II., which show 

 that the fall of conductivity by the addition of small percentages of nickel is 

 not so rapid as is the case with carbon, manganese, &c. From 0-58 to 11-39 

 per cent, of added nickel, the increase of sp. resistance is fairly uniform, being 

 at the rate of 1-6 microhms for each 1 per cent, of nickel added to the iron, 

 a rate that only slightly diminishes even in the alloys containing up to 24 per 

 cent, of nickel. When, however, carbon, silicon, or manganese are also present, 

 even in comparatively small quantities, a considerable reduction of conductivity 

 occurs. Hence the conductivity of the specimens given in Grroup 3 would, 

 especially in the low percentages of nickel, have been of a higher order had 

 the specimens been able to be manufactured without the admixture of the 

 foreign bodies named. (See also p. 91.) 



The following experiments show that the addition of a small quantity of 

 nickel does not have much effect on the conductivity of a poor steel. Two 

 specimens, 1420 A and B, were made as nearly alike as possible, except that 

 B had 1 per cent, of nickel added to it. In comparing the conductivity of 

 the two specimens, that which contained the nickel was found to be almost 

 as good a conductor as the specimen 1420 A, which had no nickel ; the latter, 

 however, had slightly higher carbon. Much the same result was given by 

 two other specimens, 1397 A and B, one of which. A, contained about half 

 a per-cent. of nickel, and the other had no nickel. Again, in two specimens, 

 1447 A and B, one with 12-7 and the other with 12-1 per cent, of nickel, the 

 former was found a slightly better conductor than the latter, which had, it is 

 true, a somewhat higher percentage of silicon and carbon. 



Nickel Steels (Series B). 



