66 Brown—The Densities and Specific Heats of some Alloys of Iron. 
as the values corrected for carbon; and by drawing a mean line through the 
points for the corrected values, we see that the addition of 15:5 per cent. of 
tungsten to iron decreases the specific volume of the material by 0.0139 ¢.c., or at 
the rate of 0:0009 c.c. for every one per cent. of added tungsten; and therefore 
the effect of adding tungsten to iron may be expressed as specific volume 
= 0'1269 — 0:0009 W, where W represents the percentage amount of tungsten 
present. 
If on adding one per cent of tungsten to 99 per cent. of iron, no change were to 
take place in the specific volumes of the constituents, the resultant mean specific 
volume of the material would be 0.12615 c¢.c¢., which is less than that of pure iron 
by 0:00075 c.c.; and the observed mean value of the change in the specific volume 
per one per cent. over a range from 0 to 15:5 per cent. of tungsten being 0:0009 c.c., 
a slight expansion has therefore taken place. 
TABLE V. 
SILICON STEELS. 
| Percentage Composition Specific Volume 
| Mark | C Si Density Observed | Calculated Difference 
= = exilea = — = St 3 
So Oy He 0-028 0-07 78771 0:12695 | 0:12719 0:00024 
898 E. 0:20 2°50 7°6934 012998 | 013480 000482 
898 H. 0:26 | 5°50 7°5100 0°18815 | 0°14373 | 0-01058 
In Table V. are given the results obtained from two silicon steels which 
contain 2°5 and 5:5 per cent of silicon respectively, the result for the pure iron 
8.C.I. being also put here for comparison. 
For the high percentage of silicon a distinct contraction has taken place in 
the alloy, as is evident from the column of differences in the specific volumes. 
In fig. 3 are plotted the observed values of the specific volumes, as well as the 
values corrected for carbon; and by drawing a mean line through the points in 
the corrected curve we find that an addition of 5-5 per cent. of silicon to iron 
mmereases the specific volume of the alloy by 0°00595 ¢.c., or at the rate of 
about 0:0011 ¢.c. for every one per cent. of added silicon, i.e., specific volume 
= 0:1269 + 0:0011 Si, where Si represents the percentage amount of silicon in the 
alloy. 
If no change were to take place in the specific volumes of the constituents 
when 1 per cent. of silicon is added to 99 per cent. of iron, the specific volume 
