Brown— The Densities and Specific Heats of some Alloys of Iron. (6) 
with the product of the specific heat and density of each specimen, the 
densities used being those found and recorded in Part I. of this paper. 
The percentages of carbon and the specific heats are plotted on a somewhat 
large scale in the curve, fig. 5, which shows that the presence of carbon in iron 
increases the specific heat of the material. 
By comparing specimens 8.C.I. and 1166 A it will be seen that an increase 
of 0°112 per cent. of carbon increases the specific heat of the material 0-001, 
and therefore the addition of one per cent. of carbon will increase the specitic 
heat about 0:0089. 
Taking an average and comparing the specimens marked 1166 A and 1392 G, 
it will be found that for an increase of 1:09 per cent. of carbon, the specific heat 
is increased 0:009, and therefore the increase for one per cent. of carbon is 
about 0:0083; or taking the mean line on the curve from 0 to 1 per cent. of 
carbon, the increase in the specific heat is 0:0075. If the specific heats could have 
been measured correctly to the fifth place of decimals, it might then have been 
possible to estimate more accurately the effect on the specific heat of an alloy 
produced by the addition of say 1 per cent. of another element to iron. 
The last column in the table shows that increase of carbon in the iron 
increases the thermal capacity per unit volume of the material. 
(WABI Re Nell: 
MANGANESE STEELS. 
| Percentage Composition Puecific 
Mark G | wen o pxo 
48 0-20 0:50 | 0-1180 0-9258 
4147 0:24 LOO | Orililexd 0°8987 
538 0-41 2°25 | 01155 0:9007 
39 0°36 4:00 0:1165 0:9128 
1323 C 0°15 5°40 | 0°1172 0:9189 
945 A 1-20 7:00 0:1184 0:9357 
1338 B 0:26 13-00 0:1225 0:9796 
598 1°54 18°50 0°1250 0:9884 
In Table XII. are given the specific heats and thermal capacities of the eight 
TRANS. ROY. DUB. SOC., VOL. IX., PART VI. O 
