1907-8.] 
Heusler’s Magnetic Alloy. 
403 
XXVII. — Experiments with Heusler’s Magnetic Alloy. By James 
G. Gray, B .Sc., Lecturer on Physics in the University of Glasgow. 
Communicated by Professor A. Gray, F.R.S. 
(MS. received April 6, 1908. Read June 1, 1908.) 
Introduction. 
In 1903 Heusler made the important discovery that alloys of copper, 
manganese, and aluminium are strongly magnetic. It was shown in the 
paper published by Heusler that by properly adjusting the amounts of 
the component metals present an alloy is obtained the permeability of 
which is comparable with that of cast iron. Heusler also demonstrated 
the fact that the properties of this alloy are profoundly modified by 
thermal treatment. 
Since 1903 a number of papers dealing with the subject have appeared 
in the various scientific journals. In 1905 some experiments were carried 
out on a sample of the alloy by the author of the present paper, and the 
results were communicated to the Royal Philosophical Society of 
Glasgow.* It was shown that the alloy, after quenching from a high 
temperature, possessed very peculiar magnetic properties. Thus the sample 
in the quenched condition was practically non-magnetic at room tempera- 
ture, but at the temperature of liquid air its permeability was much greater 
than that of the material in the normal, or unquenched, condition, in which 
variation of temperature produced but little effect. It was therefore 
decided to construct further samples of the alloy, and a number of rods 
were accordingly cast at the works of Messrs Stevens & Strutliers, the 
well-known Glasgow brass-founders. Specimens turned from these rods 
have been the subject of experiment from time to time in the Physical 
Laboratory of the University of Glasgow, and a great quantity of data 
have been obtained. The effect of repeated quenching upon the magnetic 
properties of the alloy has been studied in detail by Mr Alexander D. Ross, 
until lately Houldsworth Scholar of the University of Glasgow, and some 
of the more interesting results obtained by him have been communicated 
to the Royal Society of Edinburgh, j- 
* Proceedings of the Royal Philosophical Society of Glasgow , session 1906-07. 
t Proceedings of the Royal Society of Edinburgh , vol. xxvii. part ii. 
