Conductivity of Metals and their Vapours. 601 



Success was attained as follows : — 



The quartz tube took the form of an inverted Y (a b b, 

 fig. 1). It was constricted to a very small diameter at the parts 



Fkr. 1. 



dd, for a length of about 1 cm. on either side of the joint. 

 The lower parts of the limbs bb were of much larger diameter. 

 The tube was filled with mercury up to the level c, the current 

 being led in and out by iron wires ee, which projected some 

 distance up inside the arms bb. 



The iron wires terminated in brass cups ff, carrying 

 appropriate binding screws. These cups were filled with 

 sealing-wax, which cemented them to the quartz tube. This 

 sealing-wax had been sucked up the limbs while hot for a 

 considerable distance, up to the points gg, so as to fill the 

 space between the iron wires ee and the lower parts of the quartz 

 tube. The tops of the iron wires projected out through the 

 sealing-wax, making contact with the mercury. It may be 

 well to explain that the mercury was introduced through the 

 open end of a by making a vacuum in the apparatus before- 

 hand, a was then strongly sealed. The resistance between the 



Phil. Mag. S. 6. Vol. 4. No. 23. Nov. 1902. 2 R 



