LIQUEFACTION AND SOLIDIFICATION OF AIR AND HYDROGEN. 157 
in the larger one in use at Chatillon-sur-Seine it is effected by 
a screw press. 
The lever (l) when put in action is capable of giving a pressure 
of about 300 atmospheres, as indicated by the manometer (m). 
In order to increase this pressure the flywheel (v) is used, which 
acts upon a lateral screw plunger, capable of giving a pressure 
A PORTABLE FORM OF CAILLETET’s APPARATUS FOR THE LIQUEFACTION OF GASES. 
scale -g-. (From “La Nature.”) 
of 500 atmospheres. The second flywheel (v') serves to relieve 
the pressure with rapidity and cause a sudden expansion, a 
means whereby a lowering of the temperature of the gas con- 
tained in the tube may be effected to an extent of 200° C. 
(360° F.). This is the main advantage and peculiarity of M. 
Cailletet’s instrument. 
The tube (t t) is shown in fig. 2, detached from the cistern, for 
the purpose of being filled with the gas to be experimented 
upon. The apparatus for producing the gas is attached to the 
