RESEARCHES ON MAGNETOSTRICTION. 



361 



Fig. 1. 



(B) 



capillary tube (section) with reservoir for 

 filling the dilatometer with liquid is 

 shown in (13). In supporting the ovoid 

 in the tube, care was taken not to let 

 it touch the sealed end of the glass 

 tube. Two circular brass rings (a) (a') 

 were inserted in the tube, and made 

 to fit tightly against the wall of the 

 glnss. A brass plate of the form given 

 in (A) was soldered to the ring at a. 

 The ends of the ovoid were then placed 

 loosely within the triangular holes. The 

 ovoid was thus su [»ported in the central 

 line of the dilatometer without touching 1 

 the walls of the tube. A similar ar- 

 rangement was employed for supporting 

 the nickel rod within the dilatometer. 



To prevent the rusting of the iron, 

 the dilatometer was filled with a very 

 dilute solution of caustic soda nearly up 

 to the neck. The capillary tube and a small portion of the main tube 

 near the neck contained ether. When the dilatometer was all rilled with 

 water or with petroleum, the indication of the volume change was very 

 irregular, as the tine drops of the liquid stuck to the wall of the capillary 

 tube and the liquid was not sufficiently mobile. Cantone observed the 

 same thing when measuring the change of volume of a nickel ovoid. 

 It would have been easier to fill the dilatometer all with ether, but 

 there was a difficulty then in observing, owing to the great expansion 



i natural size. 



1). Cantone, loc. cit. 



