658 



REPORT— 1892. 



melting ice, toiling water, and sulphur vapour respectively, the other junction 

 being meanwhile at ordinary temperatures. 



The arrangement adopted for obtaining the sulphur vapour and the tempera- 

 ture assigned to it were those published by Messrs. Callander and Griffiths.' 



4. The electrical connections used for measurmg. the induction effects are 

 diagrammatically represented below (fig. 2). 



5. Eight distinct disturbances were dealt with. Some of them were eliminated, 

 others measured, and the necessary correction applied when deducing the true 

 effect due to induction. 



6. The result obtained may be exhibited by a curve whose abscissfe are the 

 temperatures of the magnetite, and whose ordinates are proportional to the induc- 

 tion effects due to its presence, the impressed magnetic field being constant. 



Commencing at ordinary temperatures, it is seen, from the curve, that the 

 susceptibility for the specimen used rose gradually at first with increase of tem- 

 perature, reached a maximum at 325° C, then fell away, being zero at 557° C 



Fig 



2. — Curve showing the variation of the magnetic susceptibility of magnetite 

 with temperature. Impressed magnetic field constant. 





O'C 



SOO' 



The sharp peak in the curve at 325° C, though apparently anomalous, was 

 confirmed by a careful repetition of the measurements in that region. It cannot 

 therefore be regarded as due to experimental errors. 



7. The impressed magnetic field (treating the primary solenoid as infinitely 

 long) was 4-8 c.g.s. units. The actual field within the specimen of magnetite 

 (when cold) was of the order 3'4 c.g.s. units. 



8. The determination of the absolute values of the permeability for the various 

 temperatures is not yet completed. When this has been done we hope to publish 

 a fuller account of the methods and result of the investigation. 



13. On the Spednim of Liquid Oxygen, and on the Refraction Indices of 

 Liquid Oxygen, Nitrous Oxide, and Ethylene. By Professor G. D. 

 LiTEiNG, F.B.S., and Professor J. Dewak, F.B.S. 



WEDNESDAY, AUGUST 10. 

 The following Papers were read : — 



1. Interim Meport of the Committee on Recalescence. 



' 'On a Determination of the Boiling Point of Sulphur, and a Method of 

 Standardising Platinum Resistance Thermometers by reference to it ' {Proc. Boy. 

 ^ti;., vol. xlix., Dec. 18, 1890, p. 56). 



