The Scott systems, fundamentally, are three in number. In the one the waste animal products are digested with open steam in conjunction with a vacuum; the second method comprises the _dry_ rendering of edible fats under vacuum; while the third practice is the extraction of the grease by what is known as the solvent system. Each possesses its individual features, making direct appeal to the situation to which it is most eminently adapted, and, to a certain degree, the three respective methods may be said to represent an equal number of progressive strides towards maximum efficiency, with the solvent process constituting the pinnacle of success so far achieved in this province from the simple fact that it reduces the loss of fat to 1 per cent. absolute. However, it is difficult to lay down any hard-and-fast rule concerning the selection of any of these three processes because, in deciding a question of this character, full consideration must be given to the class of material to be handled. For instance, although the dry rendering system under vacuum is especially applicable for the reclamation of edible fats, it is not to say that the first, or open steam, process is only adapted to the production of non-edible fats. As a matter of fact there are certain classes of offal which are not suited to dry steam rendering. The fat contained in such refuse can be most advantageously extracted only by the open steam process. This particularly applies to the offal produced in the large killing establishments, where such refuse can be dealt with in the fresh condition. The dry steam rendering process is particularly applicable to the production of fine or high grade edible fats. The finest fat recovered from an animal source is that known as “Oleo” margarine or “Premier Jus.” This is rendered from the very finest crude fat obtainable, and in order to ensure super quality being obtained the conventional treatment is one demanding extreme care so that its inherent qualities may not suffer the slightest injury. The general practice is to mince the raw material very finely and then to treat it in hot water-jacketed pans at a very low temperature, every attention being observed to prevent the temperature rising above a rigidly predetermined point. In these circumstances it will readily be observed that the process is necessarily somewhat costly and occupies appreciable time. But by means of the dry rendering process under vacuum the raw material may be subjected to very high temperatures, and that without the product being impaired in any way. In fact, it is equal in every respect to that obtained by the orthodox process, while, of course, it is far more expeditious and cheaper.