96 Barrett, Brown & Haprietp—On the Electrical Conductivity and 
CLASS III. 
Effect of three or more Elements added to Iron or Steel. 
This class exhibits the effect of the addition of three or four elements to 
steel. 
Group 23.—CopaLt-MANGANESE-SILICON STEELS. 
Mark. Percentage Composition. Conductivity Copper=100. | Specific resistance (calculated). 
: 7 : 
Co | Mn Si | C | Unann. Ann. Unann. | Ann. 
1209 © 18 | 10 064 | 025 | 6:3 7:4 2773 | 28:2 
| | | 
1209 F 7:0 | 0°8 0°80 | 0:52 | OL 56 33°6 | 30°7 
Hitherto no alloys of steel have been examined containing cobalt; the 
effect on the conductivity produced by the addition of this element closely 
resembles that produced by nickel, as will be seen by comparing this group with 
Group 3, p. 78. 
The next specimens show the effect of adding copper to a nickel-manganese 
steel and to a chromium-tungsten steel. 
Group 24.—NickeL-ManGanesz-Coprer STEEL, 
| Mark. Percentage Composition. Conductivity Copper=100. | Specific resistance (calculated). 
= - ~ (a — = 
| Ni | Mn Cu C Unann. Ann. | Unann. | Ann. 
1261 A 2:9 en ee lco 2°9 0-17 5°38 GQ | sry | 24:9 
Group 25.—CuRomiuM-TuNGStEN-CoPpPER STEEL. 
Mark. | Percentage Composition. Conductivity Copper=100. | Specific resistance (calculated). 
Cr W Cu | C Unann. Ann. | Unann. Ann. 
1249 A 1°75 2:0 2°0 0°48 3°5 5°95 49:0 31°3 
This alloy 1249 A was drawn into wire and its specific resistance directly 
measured in the annealed state, together with its temperature coefficient. The 
specific resistance at 16°C. was found to be 31:6 microhms per c.c. As will 
be seen, this result closely agrees with that deduced from its conductivity in the 
form of arod. ‘The percentage variation of resistance of this alloy per 1° C. was 
found to be 0:204 between 10° and 150° C. 
