i879-J 
Molecular Physics in High Vacua. 
433 
first adtion of the heat I have coated the tube with wax. 
I will put the apparatus in front of the eledtric lantern 
( d ), and throw a magnified image of the tube on the 
screen. The coil is now at work, and the focus of 
Fig. 17. 
molecular rays is projedted along the tube. I turn the 
magnetism on, and draw the focus on the side of the glass. 
The first thing you see is a small circular patch melted in 
the coating of wax. The glass soon begins to disintegrate, 
and cracks are shooting starwise from the centre of heat. 
The glass is softening. Now the atmospheric pressure forces 
it in, and now it melts. A hole ( e ) is perforated in the 
middle, the air rushes in, and the experiment is at an end. 
Instead of drawing the focus to the side of the glass 
with a magnet, I will take another tube (Fig. 18), and allow 
the focus from the cup-shaped negative pole (a) to play on 
a piece of platinum wire ( b ) which is supported in the 
centre of the bulb. The platinum wire not only gets white- 
hot, but you can see sparks coming from it on all sides, 
showing that it is adtually melting. 
Here is another tube, but instead of platinum I have put 
in the focus that beautiful alloy of platinum and iridium 
which Mr. Matthey has brought to such perfedtion, and I 
think that I shall succeed in even melting that. I first turn 
on the indudtion-coil slightly, so as not to bring out its full 
power. The focus is now playing on the iridio-platinum, 
raising it to a white-heat. I bring a small magnet near, 
