On the Magnetic Susceptibility of Liquid Oxygen. 311 



nerve given in the third column, both the commencement and the 

 culmination of the initial change are retarded, the propagation rate 

 in this nerve at a temperature of 6 C. being slowed to 6 metres per 

 second. A comparison of the fourth and fifth columns shows the 

 retardation in the anodic as compared with the acceleration in the 

 cathodic extrapolar region. Finally the time relations and the 

 relative E.M.P. of the prolonged effect present in the instances given 

 in the second and fourth columns may be compared with those of 

 the initial change present in all the examples. It will be seen that 

 the change producing the prolonged tail of the photographic record 

 is one which differs from that producing the initial spike in the 

 following important particulars : it develops slowly, taking from 

 O'OOG to O01 second to culminate, its maximum E.M.F. is only one- 

 tenth of that of the initial change, and it subsides slowly. It is not 

 present in the instances given in columns I, III, and V. 



In a more extended communication the authors hope to bring 

 forward other features of the response of nerve, particularly the 

 characters exhibited by the records of the changes produced by a 

 series of stimuli and of those produced during reflex discharge of the 

 central nervous system. 



" On the Magnetic Susceptibility of Liquid Oxygen." By J. 

 A. FLEMING, M.A., D.Sc., F.R.S., Professor of Electrical 

 Engineering in University College, London, and JAMES 

 DEWAR, M.A., LL.D., F.R.S., Fullerian Professor of 

 Chemistry in the Royal Institution, London, &c. Received 

 May 9, Read May 12, 1898. 



In a previous communication* we have described the initial 

 investigations made by us to determine directly the numerical value 

 of the magnetic permeability of liquid oxygen, and we there indi- 

 cated that we hoped before long to present to the Royal Society the 

 results of other experiments made by a different physical method 

 which we anticipated would enable us to state whether liquid oxygen 

 has a constant magnetic susceptibility, or whether, like a ferro- 

 magnetic substance, its magnetic susceptibility alters when subjected 

 to different magnetic forces. 



We have recently obtained results which, though limited to a 

 certain range of force, we think afford fairly trustworthy values of 

 the magnetic susceptibility of liquid oxygen under magnetising forces 

 varying from 500 to 2500 C.G.S. units, and place them therefore on 

 record. 



* ' Koy. Soc. Proc.,' 1896, vol. 60, p. 283, " On the Magnetic Permeability of 

 Liquid Oxygen and Liquid Air." 



VOL. LXIII. 2 A 



