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VIII. The Magnetic Properties of the Alloys of Iron and 

 Aluminium. — PART I. By S. W. RlCHARDSON, D.Sc, 

 late 1851 Exhibition Research Scholar ; Lecturer and De- 

 monstrator in Physics at the University College, Nottingham *. 



Contents. 

 § I. The Introduction. 

 § II. A discussion of the method used for the magnetic measurements, 

 and a description of the apparatus. 

 § III. An account of the method used for determining- the temperature. 

 § IV. An account of the methods used for varying the temperature. 

 § V. The data obtained and some remarks upon them. 



§ I. The Introduction. 



ri'HE experiments made by Hopkinsonf on alloys of iron 

 JL and nickel led to such striking results that the author 

 thought that experiments of the same nature on other alloys 

 of iron might contribute some interesting facts to our know- 

 ledge of Magnetism. Accordingly a series of experiments 

 were undertaken on some alloys of iron and aluminium. An 

 account of the earlier experiments on these alloys, performed 

 at the Cavendish Laboratory during the years 1897 and 1898, 

 is given in this paper ; the later experiments being reserved 

 for a subsequent communication. 



The alloys were made to the author's order by the British 

 Aluminium Company. Considerable difficulty was ex- 

 perienced at first in obtaining satisfactory specimens, the 

 ones first made being very brittle and liable to split when 

 smartly struck. This was no doubt due mainly to rapid 

 cooling. After taking suitable precautions against this, 

 however, sufficiently durable specimens were obtained — unless 

 the amount of aluminium approached 30 per cent., in which 

 case the alloys gradually disintegrated to fine powder with 

 the evolution of acetylene gas. 



The specimens actually investigated contained 3*64, 5*44, 

 9 '89, and 18'47 per cent, of aluminium respectively. The 

 first was comparatively soft and could easily be turned in a 

 lathe; but the other three (in which the carbon was in the 

 combined form) were extremely hard, and it was found im- 

 possible to cut them with ordinary tools. The rings used in 

 the experiments were obtained by casting the metal into a 

 disk and boring out the central part of this by means of a 

 rotating copper tube fed with emery-powder and oil. 



* Communicated by the Physical Society : read October 27, 1899. 



f * Proceedings of the Royal Society,' December 1889, January and 



