LIQUEFACTION AND SOLIDIFICATION OF AIR AND HYDROGEN. 159 
pansion, and its condensation succeeded as might have been 
expected. 
Fig. 3. 
m. raoul pictet’s machine for the liquefaction of gases. (From “La Nature.”) 
M. Pictet's Machine . — In a former number of the “ Popular 
Science Review 5 ’ (July 1877) the beautiful freezing-machine of 
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