Brown—The Densities and Specific Heats of some Alloys of Iron. 9 
of the pure iron §.C.I. for comparison. rom the first two specimens in the 
table, it would appear that the addition of 2:43 per cent. of silicon increases the 
specific heat of the material about 0:0066, or at the rate of very nearly 0-003 for 
every one per cent. of added silicon; whilst a further addition of 3 per cent. 
of silicon has very little effect on the specific heat. 
And since silicon added to iron decreases the density and increases the specific 
heat, the thermal capacity per unit volume remains fairly constant, as indicated in 
the last column of Table XV. 
TABLE XVI. 
CHROMIUM STEELS. 
| 
Percentage Composition Specific | | 
eat | 
Mark C Cr o | pxo 
| | 
993 | Ooo 2°00 Os12025 9) 91029329 
1177 I | 0-48 3-25 | 01169 | 0:9078 
| 
1177 N | 1:09 9°50 0-1206 0:9290 
| | 
| | | 
The results for the three chromium steels in Table XVI. are somewhat irregu- 
lar, the effect of the chromium on the specific heat being masked by the high 
percentage of carbon present. Judging from the first and third specimens, which 
have approximately the same amount of carbon, the specific heat is not altered by 
the addition of 7:5 per cent. of chromium. The effect is probably entirely due 
to carbon, seeing that in the case of the second specimen, marked 1177 I, the 
amount of carbon is about half of that in the other two specimens, and its specific 
heat is reduced. In fact, if the results for these chromium steels are plotted on 
the plate, fig. 5 of the carbon steels, they will all lie very nearly on that curve, 
showing that chromium has little or no effect on the specific heat of the iron when 
a high percentage of carbon is present. 
[Taste XVII. 
