116 Barrett, Brown, AND Haprirtp—Researches on the 
In Table IV. are given the results with some tungsten, aluminium, and silicon 
steels. Tungsten was found to have the least effect of any element, so far tried, 
in reducing the electrical conductivity of iron, whilst aluminium had the greatest 
effect. The same thing comes out here: the curve for the aluminium-iron alloys 
is shown in fig. 1. The last specimen in Table IV., 1414 B, was an alloy which 
was found to have the highest electric resistivity in the whole series of upwards 
of 100 iron alloys; it is also found to have the highest thermal resistivity 
of any of the alloys tested. This alloy, which isa nickel manganese steel, owing 
to its very low heat-conducting power, might be found invaluable for the 
inner lining of the cylinders of steam-engines; such a lining would, as is well 
known, greatly increase the efficiency of the steam-engine. 
TABLE LY. 
Relative Conductivity. | 
Mark. Principal Constituents. es E23 Thermal. Electrical. 
B | 99-71 Fe, Mew) POL re 15:0 225 1000 | 100-0 
1392H 99:02 Fe; 0-78 CG, . : ; 13°5 182 81:0 75:0 
1294F 98:73 Fe; 1:00 W, . 4 , 13:1 172 76:4 72:3 
1294H 95:94 Fe; 3:50 W, . ‘ : 12-2 149 66:3 61:0 
1167D | 98:98 Fe; 0:75 Al, =. 11:7 137 60:9 49°5 
1167 I 94:08 Fe; 5:50 Al,. . : 77 61 27:2 15°9 
898H | 94:24Fe;550Si,. . . 8°5 72 32:0 16-7 | 
1414B | 69°36 Fe; 25-0 Ni; 5-04 Mn, . 71 50 OQ |) GPS 
In Table V. is given a miscellaneous collection of steel alloys, all containing 
copper. It will be noticed that none of them has a higher thermal or electrical 
conductivity than the iron standard. But unfortunately these alloys all contain 
either high carbon or manganese impurity; to ascertain the true effect on the 
conductivity of iron produced by alloying it with copper, pure alloys must be 
made, or a comparison instituted with the conductivity of a carbon steel having 
the same percentage of carbon or manganese. Under these circumstances it will 
probably be found that copper has very little effect on the conductivity ; it may 
slightly raise it. 
