Physical Properties of an Extensive Series of Alloys of Iron. il? 
TaBLe V. 
Principal Constituents. Relative Conductivity. 
Mark. Fe. C. Ni. Mn. Cr. | Cu. L. L?. Thermal. Electrical. 
B om} — | =| —= | = | & 1260 | opeo | TOM | ton 
1264 A 99°37 0:68 — | 0°36 — eG) |) Theses 182°0 81:0 72°8 
1264 B 96:59 | 0°59 —= | 0532 — 2°50 | 138°9 192:0 85:5 UBS 
1263 CG 95°92 0-17 == | iy — 2°87 | 12°8 164:0 72:9 62:1 
1255 A 91:60 0°85 — — 07/5) 1°80 | 10°5 112:0 49°8 34°8 
1252 B 91°32 0:18 5:75 | — — 7/65) 9°4 88°5 39°4 28°6 
1240 96°25 | 0°25 — 200 — iLeX0) 3) Tiled 123:0 64:7 43:0 
1260 A 88°61 0°64 == | SOO — 97/5) 79 62°5 27°8 21:0 
As already stated, all the foregoing results can only be regarded as 
preliminary, the method of experiment not allowing more than approximate 
accuracy. We next adopted the method of obtaining the gradient of tem- 
perature by means of thermo-couples lashed on to the rods, one end of the 
rod being kept at a uniformly high temperature. This part of the research 
was entrusted to Mr. 8. A. Edmonds, a senior student in the physical laboratory 
of the Royal College of Science for Ireland, who, on completing his College 
course, obtained a research Bursary. The results, whilst in general agreement 
with those already given, are of a higher degree of accuracy, owing to the 
method employed. 
To render the emissivity as far as possible uniform, the surface of each rod 
was cleaned in weak acid, then washed and brightened by friction with fine 
emery. One end of the rod was heated by means of an asbestos-jacketed steam 
cylinder, the rod passing through a screwed stufling-box, and supported in a 
horizontal position. The portion of the rod outside the steam cylinder was 
enclosed in a trough made of a double thickness of cardboard separated by cotton 
wool, a cover being placed over the trough, so that the cooling effect of air 
currents was as far as possible avoided. ‘The thermo-couples employed to take 
the temperature along the rod were made of German-silver and iron wires of 
No. 28 B.W.G.; the tightly twisted ends of each couple were lashed round the rods, 
and the free ends dipped into a pair of mercury cups immersed in a large mass of 
TRANS. ROY. DUB. SOC., N.S., VOL. VIII., PART IX. Xx 
