Messrs. PL Nagaoka and K. Honda on Magnetostriction. *2ft7 



there was difficulty in the observation owing to the greater 

 expansion of the liquid due to the heating f the coil. We 

 consider that the present mode of filling the dilatometer pro- 

 vided with fine capillary tube can be successfully applied 

 for other purposes of a similar nature. 



Fi- 1. 



J 



mm - Ether 

 Water 



The ovoid was placed in the middle of the magnetizing coil 

 and the rise or fall of the meniscus in the capillary tube was 

 observed by means of a microscope with micrometer ocular. 

 Although the resistance of the coil was only 0*6 ohm, the 

 heating effect was considerable, so that only an instantaneous 

 observation could be made. The difficulty was to a great 

 extent overcome by passing the current for some time in the 

 coil ; the ovoid was then demagnetized by the method of 

 reversals ; waiting for some time, the meniscus became 

 stationary, the magnetizing current was then made and the 

 reading taken. The measurement was made in a cellar with 

 gaslight at some distance behind the capillary tube ; by this 

 arrangement the meniscus was sharply defined. 



The following table gives the determination of the change 

 of volume in iron ovoid and cylinder by magnetization. 



