288 Proceedings of the Royal Society of Edinburgh. [Sess. 
wool. The tube, containing the specimen, was then placed between the 
conical pole-pieces of a very powerful electromagnet. On exciting this 
magnet the specimen was exposed to a magnetising field of 4400 C.G.S. units. 
The tube was next withdrawn and mounted on a special stand so that the 
specimen lay at a considerable distance from a magnetometer needle, and 
with its axis lying along the magnetic east and west line passing through 
the needle. By means of the magnetometer the magnetic moment of the 
specimen was measured under the following conditions : (1) at room 
temperature immediately after being magnetised, (2) after cooling the 
specimen to -190° C., (3) after the specimen had regained room temperature, 
(4) on re-cooling to —190° C., and so on. This is the procedure of Dewar 
and Fleming. 
The tube was now withdrawn and placed in position between the poles 
of the electromagnet and the specimen brought to the temperature of 
liquid air. The magnet was then excited and the tube withdrawn and 
placed once more in position on the magnetometer. The magnetic moment 
of the magnet was observed (1) at — 190° C. following on the magnetisation 
of the specimen, (2) after the specimen had warmed to room temperature, 
(3) on cooling once more to — 190° C., and so on. 
The results obtained differ from those observed by Dewar and Fleming 
in that the reversible condition described above is arrived at after the first 
warming up of the specimen from — 190° C. to room temperature, and the per- 
centage change in magnetic moment then brought about by cooling from room 
temperature to that of liquid air is much greater than is the case for a 
specimen which has been magnetised initially at room temperature. 
The following table gives the dimensions and chemical compositions of 
the specimens employed in the experiments : — 
Dimensions and Chemical Composition of Specimens Employed. 
Description of 
Material. 
Length 
of 
Speci- 
men in 
Cms. 
Dia- 
meter of 
Speci- 
men in 
Cms. 
Mass 
in 
Grins. 
Percentage Composition. 
Car- 
bon. 
Man- 
ganese. 
Sili- 
con. 
Sul- 
phur. 
Phos- 
phorus. 
Steel wire 
7-7 
0-27 
3-36 
0-755 
0-660 
0-066 
0-017 
0-027 
Special hard steel . 
7-2 
0-96 
40-0 
1-321 
0-339 
0-143 
0-023 
2-745 
Manganese steel 
7-0 
0-96 
39-0 
0-71 
6-00 
... 
ii ii 
7-0 
0-96 
39-0 
0-60 
12-00 
