liquefy  
verb (also liquify) uk/ˈlɪk.wɪ.faɪ/ us/ˈlɪk.wə.faɪ/
  (SUBSTANCE)      
 [ I or T ](使)成为液体,使液化 
to (cause a gas or a solid to) change into a liquid form
  Gases liquefy under pressure. 气体在压力作用下会液化。 
 To liquefy it, the gas is cooled to minus 260 degrees.
 - More examples
 - After 5 or 10 minutes, the sugar will start to liquefy and form large chunks.
 - The body was so badly decomposed it had started to liquefy.
 - Liquefied natural gas is natural gas that has been supercooled into a liquid state.