of Palladium caused by Absorbed Hydrogen, 



135 



4. The Torsion- system. 



The torsion-head was fixed to a bridge built on a slate 

 bench, the space under the bridge being enclosed in a 

 draught-tight chamber with a glass back. The space 

 between the magnet-coils wis also enclosed in a chamber, 

 whose top came close under the bench. The torsion-stem 

 passed through a hole in the bench, lined by a tube passing 

 into the magnet-chamber close to its back wall. 



R (fig. 2) represents the flat end-piece of the rod of the 

 torsion-head. Pt.Ir. is the torsion-wire of platinum-iridium, 

 a substance which has been found to give a very constant 

 zero, Its diameter was *05 mm., its length about 5 cm. 



Fv-. 2. 



^t 



The torsion-wire was connected to one end of the fine wire 

 of the coil A. The other end of the coil-wire passed outside 

 the tube g, making a couple of turns round the tube on the 

 way, and was connected to a phosphor-bronze spiral, Ph.JBz., 

 enclosing the torsion-wire, and waxed at the top to R. Into 



