At the large cattle-slaughtering establishments of North and South America, and at the sheep-killing stations in Australia and New Zealand, the residues from which the edible fat has been recovered by the open steam process are turned over to the solvent extraction plants which have now been introduced to form an integral part of the waste-recovery system, the value of the invention being fully appreciated. At first the practice was to dry the residues from the digesters before committing them to the extraction plant, but since it was found superfluous to carry out such a preliminary, the residue is turned over from the open steam digester where the edible fats are obtained to the solvent extraction plant, the idea of course being to secure the proportion of fat escaping recovery in the digester. In this manner 99 per cent. of the fat contained in the crude waste is obtained, but the proportion reclaimed from the practice of the solvent extraction process is set aside for manufacturing purposes--conversion into soap and other utilitarian commodities. In the course of digesting the fresh fat with open steam a considerable quantity of the “stick” liquor is precipitated, and its recovery for size is fully justified. In the crude form this liquor is somewhat weak, but by means of the Scott multiple-effect vacuum evaporating plant it can be concentrated to any required degree of density. This product is blended with the meat-meal from the solvent extraction plant in a suitable vessel and is then dried to a powder, the ultimate meal being high in ammonia. In the case of the offal which is not suitable for the production of an edible fat, recourse to the open steam digester is eliminated. The refuse, along with the condemned meat, is consigned directly to the extraction plant to be dealt with in one operation. A similar practice is followed at the large pig-killing establishments. At one installation in South America, where there is an impressive illustration of British ingenuity and enterprise in regard to waste recovery upon the Scott principle, the tallow produced is immediately dispatched to the adjoining soap works--also a British installation--where the glycerine is recovered and soap is produced. In this instance therefore we have a powerful example of a self-contained establishment completely equipped for the recovery of the whole of the by-products incurred in the course of its normal operations and to the utmost advantage.