
IMPORTANT NEW EXPERIMENTS 139 
Thus prepared, the tube should be just half full 
of liquor potasse. Its length will have been 
diminished as f" 
much as possible; 
and its tip is so 
arranged that it 
| may be easily 
broken off by a 
slight mechanical 
shock. These 
last steps in the 
preparation of 
the liquor- 
potasse tubes are 
best carried out 
with the aid of a 
very small spirit- | 
lamp flame, as omssesmmemeenasscliid 
they require to FIG. 4. 
be done slowly PANO PEE tubes, with capsule and stand. 




and with care. On the one hand, it is necessary that 
the bent part of the tube should be weak enough to 
break readily when jerked against the wall of the ex- 
perimental vessel in which it is afterwards enclosed ; 
and, on the other, it must not be so much weakened as 
to make it break too easily or be unable to bear the 
internal strain which it will have to undergo during 
its immersion in boiling water. This, in fact, is the 
final stage in the preparation of the liquor-potasse 
tubes. A number of them, after they have been 
hermetically sealed, are to be placed in a suitable 
vessel containing warm water; and they are then to 
