But we need labour no longer in ignorance. Modern science, as represented by chemistry and engineering, is able to offer an equipment capable of extracting the whole of the oil content down to 1 per cent. In other words, 99 per cent. of the oil contained in the raw offal and scrap can be recovered both cheaply and easily. The loss of such a minute fraction as 1 per cent. undoubtedly represents a remarkable chemico-mechanical achievement. The new process completely coincides with the dictates of contemporary science. The fundamental features are cooking the refuse under vacuum and the ultimate extraction of the oil by the aid of a suitable solvent such as benzine or other equally volatile spirit, or the benzine extraction system may be used from the very beginning, in a single and complete process. I have described this highly ingenious system in a previous chapter together with the system of operation followed. Obviously while the highest efficiency can only be derived from the installation of the complete plant, the processes being interrelated, the designer found it possible to modernize some of the old-fashioned and wasteful equipments to a very striking degree by the introduction of certain features to meet the exigencies of the moment. A very convincing illustration of what can be achieved in this connection may be related. A firm specializing in the exploitation of herring offal desired to extend its plant, but was baulked in its intentions owing to the various restrictions which were in force. Accordingly it was compelled to consider the situation of how to derive more from the existing facilities without adding to them, at least only to an insignificant degree. At first sight this may seem to have presented a somewhat intricate, if not actually impossible, undertaking. Yet it was effected. The modified arrangement introduced is decidedly interesting. The offal is cooked in the steam-jacketed cooker, as much as possible of the oil being skimmed from the mixture at the critical stage of coagulation. The sediment, or mud-like residue, is then transferred to an extractor where the remaining oil is recovered. This converts the residue into a still stiffer substance to be finished off in the ordinary steam-jacketed drier, instead of being completely dried in the extractor as originally designed. This solution has proved to be exceedingly simple and eminently efficient. Although considerable handling is involved the extracting capacity of the plant has been nearly doubled. The advantages to be recorded are:-- (1) Ability to handle very much larger charges of waste when not reducing the material to a dry meal; (2) Reduction of the raw material to the extent of the oil removed from the cookers; (3) Reduction of the time required for the oil extraction by approximately 50 per cent.