PROPERTIES AND USES OF NICKEL STEEL. 687 
The foregoing table also shows that the elastic limit and 
strength of pure iron is about the same in the cast and 
forged specimens, and that the ductility of the forged iron 
is greater. The effect of annealing pure iron appears to be 
a reduction of the elastic limit and strength, 5 a affect- 
ing its ductility to a great extent. 
The cast nickel was harder to file than the forged, although 
its tenacity is so much less. The forged nickel is much 
stronger and more ductile than the cast, which is only 
slightly affected by annealing; whereas the elastic limit is 
greater in the forged than in the cast nickel, but is reduced 
to one-half by annealing. The specific gravity of the cast 
nickel in these tests was 8-839, and of the forged nickel 
8-826, which differ slightly from the values given by 
Moisson—8 - 3 for cast, and 8-8 for forged nickel. 
Coefficient of Hlasticity—The coefficient or modulus of 
elasticity of alloys of cast nickel and iron having various 
percentages of nickel have been investigated by the German 
Commission, and reported on by Professor Rudeloff. The 
results, reduced to English units, are recorded in the follow- 
ing table: — 
Coeflicient of Elasticity 
Percentage of Nickel. in tons per square 
inch. 
0°05 13,880 
0°91 13,240 
2-05 13,680 
3°01 13,720 
3°98 - 19.780 
4°92 12,660 
7°84 12,280 
15°60 10,280 
29-78 7800 
59-60 9200° 
93°52 | 11,200 
98°56 10,720 
A similar investigation has also been made by M. Ch.-Ed. 
‘Guillaume, but the experiments were made on bars sup- 
ported at each end and loaded in the centre, whereas Prof. 
Rudeloff’s results were obtained by subjecting the bars to 
