A pressure-filter is disclosed along with its peripheral equipment that permit the automatic controlled operation of the filter for extracting liquids from a fluid liquid/solid slurry and for the formation of a substantially dry filter cake. The efficiency of the filter apparatus is increased by the use of hot gas as a material for treating the cake within the filter for extracting the liquids as filtrate. The hot gas may be hot air, hot inert gas, steam, or combinations thereof in controlled sequences. The filter is adapted to be able to operate under vacuum or elevated pressure and at elevated temperatures.