76 Brown— The Densities and Specific Heats of some Alloys of Iron. 
manganese steels, and the manganese curve in fig. 6 shows the specific heats 
plotted against the amount of manganese present in the specimens. 
By comparing the specimen marked 48 in this table with the specimen 8.C.I. 
in Table XI., which is practically pure iron, it would appear that by adding 0:5 
per cent. of manganese to the iron the specific heat is dereased, and adding 
0:5 per cent. more of manganese decreases it, whilst after that point the addition 
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Percentage of added element. 
Fic. 6—Maneanese, NicKEL, AND TUNGSTEN STEELS. 
of manganese increases the specific heat at a fairly uniform rate. By com- 
paring the specimens containing one per cent., and 18°5 per cent. of manganese 
respectively, it is seen that 17:5 per cent. of manganese added to iron increases 
the specific heat by 0:01. Also for the same percentage range of manganese, the 
thermal capacity per unit volume is increased at a nearly uniform rate, as shown 
in the last column of Table XII. 
° 
