830 Miss M. B. Moir on Magnetic Properties of a 



A more convenient method of making a comparison 

 between theory and experiment is furnished by the use of a 

 thin film of some substance rich in hydrogen, such as paraffin 

 wax or indiarubber. When « particles fall on such films, H 

 particles may be expacted to be ejected, and experiments have 

 shown that this is actually the case. The observations are at 

 present being continued so as to study the distribution and 

 number of ejected H particles when a parallel beam o£ 

 a particles of known velocity passes through these films. 



In conclusion I beg to express my indebtedness to Mr. W. 

 C. Lantsberry for his very efficient help in many of the 

 observations, and to Sir Ernest Rutherford for his many 

 kind suo-D-estions. 



oo 



Physical Laboratories, 



University Manchester. 



XCII. The Magnetic Properties of a Graded Series of Chrome 

 Steels at Ordinary and Low Temperatures. By Margaret 

 B. Moir, M.A.j B.Sc, Carnegie Research Fellow in the 

 University of Glasgow *. 



rj^HE influence of temperature upon the magnetic pro- 

 JL perties of iron, steel, nickel, and cobalt has been 

 investigated by numerous experimenters, perhaps the most 

 notable work being that carried out by Rowland |, Baur +, 

 and Hopkinson §. 



It is now well known that the effect of raising the tem- 

 perature of a specimen of iron or steel is to increase its 

 susceptibility to magnetism for low values of the magnetizing 

 force and to diminish it for high values. It is to be expected 

 then that, if the temperature of a test-piece be lowered, the 

 effect should be exactly reversed, and the susceptibility 

 should be diminished for low and augmented for high fields. 

 That such is actually the case has been shown for various 

 magnetic materials by Honda and Shimizu ||, and more 

 recently by Gray and Ross If, ^"ho have all used the tem- 

 perature of liquid air, —190° C, as the low temperature at 

 which they have made their investigations. They have 

 shown also that, while alike in this one respect, different 

 materials differ very considerably both in the amount of 



* Communicated by Professor A. Gray, F.R.S. 



t Phil. Mag. xlvii. p. 321 (1874). 



t Wied. Ann. xi. p. 394 (1880). 



§ Proc. Hoy. Soc. xlv. p. 318 (1889). 



|| Phil. Mag. x. p. 548 (1905). 



% Trans. FaTaday Soc. vol. viii. part i. (1912). 



