Magnetic Permeability of various Alloys of Iron. 



73 



CLASS I. 



Carbon Steels. 



Beginning witli the Carbon steels, it is necessary to subdivide the specimens 

 into two series, one of whicli (A) is freer from other elements, such as manganese 

 and silicon, than the other series (B): as might be expected, the former has a 

 higher conductivity than the latter. Tlie chemical analysis in percentages for 

 each specimen is given in the tables following, iron being understood in all cases 

 to make up the total to 100. The last column gives the calculated specific 

 resistance in microhms per c.c. at about 17° C. The letters Unann. and Ann. 

 signify the conductivity in the unannealed and the annealed conditions respec- 

 tively. 



Group 1. — Carbon Steels (Series A). 



It will be seen that the conductivity decreases as the percentage of carbon 

 increases, at first very rapidly, so that the conductivity of chemically pure iron 

 would certainly be higher than the specimen S.C.I. The resistance of the 

 specimen L.S.S. is a little greater than B., owing to the presence of a larger 



* A complete analysis of tlie first three specimens was made as follows : — 



