88 Barrett, Brown & Hadfield — On the Electrical Conductivity and 



Grroup 10. — Nickel-Chromium Steels. 



The effect of chromium on the conductivity of these steels is well seen by 

 comparing 1286 A and C, very similar alloys, except that the latter has 1 per 

 cent, more chromium in it : an addition that increases the resistance 3'8 microhms. 

 Compare also 1286 C and 1210 D, which mainly differ in the latter containing 2'75 

 per cent, more chromium — a difference that increases the resistance 2'6 microhms 

 for each I per cent, of added chi'omium ; the resistance increasing at a slower rate 

 as the alloy becomes richer in chromium (cf. Group 7). The last specimen, 1450, 

 has nearly 10 per cent, more nickel than the one preceding it, 1210 D, and also 

 higher carbon and manganese, hence its conductivity is lower, notwithstanding the 

 reduction of 2^ per cent, in the chromium. A much greater effect is produced on 

 the conductivity by silicon added to a nickel steel, as follows : 



Group 11. — Nickel- Silicon Steels. 



As was the case with the nickel chromium steels in Group 10, the large quantity 

 of nickel present in the first two specimens above, 1447 A and B, has a less effect 



* This specimen also contained 0'54 per cent, of manganese. 



f These two specimens also contained 0-61 per cent, of manganese. 



