Now, no matter how persistently and effectively the lessons of economy may be preached in the kitchen and at the table as much in the home as in the army, and notwithstanding the infinitesimal degree to which the proportion of spoiled food may be reduced by the introduction of superior methods and skill, a certain amount of waste is unavoidable. It cannot be overcome in its entirety. Tastes differ so widely that odds and ends are certain to be left untouched upon the plate, while a certain accumulation of gristle, bone, fat and other inedible portions must be expected. The residue upon the individual plate may be so insignificant as to render a second thought concerning its probable value superfluous. But, multiply that individual plate and its contribution of waste by the tens of thousands of plates in use at one time, as in the army, and it will be realized that, in the aggregate, the fragments assume a very imposing volume. Furthermore, in the kitchen where the joints are cut up, the accumulation of pieces is striking. Lastly, in washing up the plates, dishes and other utensils what an avenue is offered for the escape of immense quantities of fat through the sink gully? I have already indicated in a previous chapter what wealth may be lost in this manner, and how it only needs adequate reclamation methods to enable such loss to be avoided. Accordingly, contemporaneously with the reorganization of the catering and cooking issues, the exploitation of the now appreciably attenuated swill-tub contents was investigated. This residue was still being sold to the farmers, but they were not regarding their purchases with unalloyed delight. Contrary to general opinion, perhaps, raw swill does not constitute an ideal foodstuff for porkers. As a rule it is too rich in fat and so tends to exercise a debilitating and impoverishing effect upon the animals, being a frequent cause of scour. About this time a grave problem asserted itself in another field of military activity. The Ministry of Munitions had decided to speed-up the output of explosives, but such acceleration was threatened by a shortage of the indispensable constituent, glycerine. It was not a question of the facilities for the production of this essential being insufficient to cope with the demand because ample plant was available. The difficulty was the dearth of animal fat which yields the basic material in question. Soap manufacturers were also being hard-pressed for similar fats to conduct their operations. As a result of the depressing outlook the price of glycerine commenced to advance upon the market at a disconcerting rate.