The contents of the collecting lorries are distinctly heterogeneous, the vehicles being laden with swill, bones, empty tins, jam and pickle jars, bottles--in short, anything possessing an element of salvage value. In segregating the waste at the cook-house special stress is laid upon the necessity to keep all green vegetable matter, such as outer leaves, stumps and other inedible trimmings, distinct from the general swill for the reason explained later. The swill is transferred by the elevator to the upper level, where it is dumped into a capacious sink to drain. The proportion of free liquid is not pronounced, the swill being rather in the nature of a slush, whatever fat there may be present, apart from the solid pieces, being either congealed in flakes and globules, either free or clinging to the more stable substance. The superfluous water having run off the residue is permitted to fall through a trap into a hopper feeding the capacious cooker or melter. Where the height of the building does not permit the provision of an elevated draining sink the swill, dumped at ground-level, is shovelled into the melter. The melter is a cylindrical vessel or drum fitted with a steam jacket, the steam circulating at a pressure of about 80 lb. per square inch through the annular space between the inner and outer jackets. The capacity of the vessel is approximately 1,700 pounds, and the contents are kept agitated during the process by paddles mounted upon a revolving shaft forming the longitudinal axis of the drum. The cooking process drives off all remaining moisture in the form of steam, and, at the same time, liberates whatever fat may be present by melting and rendering it fluid. It gravitates to the bottom of the cylinder to make its escape through a suitable vent and pipe into the settling tank. The last-named is also steam-heated by a coiled pipe system which not only sterilizes but clarifies the reclaimed fat, which is then permitted to cool and to solidify. The swill remains in the drum for 70 to 90 minutes. By the end of this period the contents have been practically cooked, while all free fat has effected its escape. It will be observed that the steam does not come into contact with the contents, but is confined to circulation between the jackets. When withdrawn from the melter the swill resembles a stiff slush. This is transferred to a canvas bag to be dropped into a wire cage forming the inner vessel of the second machine, which is a vertical turbine extractor. The vessel when charged is closed by clamping down the lid.