THE COMBINING VOLUMES OF HYDROGEN AND OXYGEN. 
397 
terminals of which made contact with stout platinum hooks sealed through the glass 
of the outer tube. By passing a current through the wire the palladium could be 
heated to any desired temperature. 
The junction between the thick platinum tube and the glass was an excellent piece 
of workmanship carried out by Baumbach, the University glass-blower; it was quite 
free from air-bubbles and absolutely gas-tight. For a year and a half it has been 
constantly heated and cooled, and no sign of a crack has ever appeared. 
The three palladium tubes used in this work were obtained from Messrs. Johnson 
and Matthey. The first tube was made from forged sponge ; the second and third 
from fused metal. The third tube (the one figured in the diagram) contained 0'5 per 
cent, platinum and a trace of rhodium which were deliberately left in with the idea of 
increasing its mechanical rigidity. The weight of palladium in the second and third 
tubes was about 26 gr., but the third tube, the dimensions of which have already 
been stated, was made about twice the length and half the wall-thickness of the 
