Of course, the municipal authorities could not aspire to net such profits as are possible in the army. In the first place the wage problem must be taken into consideration. Under military conditions this does not arise. Fatigue parties are always available to collect the swill and to conduct its conversion into fat. But even if the practice were pursued at a loss it would redound to the distinct benefit of the community in general, because it would comply with one of the fundamental laws of National Economy and would conduce towards the reduction in the cost of living. But unprofitable exploitation would not result so long as the methods were conducted along commercial lines. Ineptitude and wastage in administration and operation alone could be responsible for any such eventuality in this connection. Happily we are becoming wiser in our knowledge: domestic organic waste is now being exploited on broader lines, as I relate in subsequent chapters. CHAPTER V INVENTION IN ITS APPLICATION TO WASTE RECOVERY The necessity to conserve our industrial resources, which is so pronounced to-day, is acting as a powerful stimulant to inventive effort. The mere circumstance that approved apparatus exist for the reclamation of wastes and are readily available to those of a thrifty or enterprising turn of mind no longer suffices to meet the situation. In the past we have been content to practise waste recovery along what may be described as satisfactory lines, but satisfactory only in so far as they represented an attempt to turn refuse to commercial account. In many instances the appliances employed have only been extemporized and, as may be imagined, are far from being efficient. They only enable a certain proportion of the available materials to be recovered. In many instances residues treated for fats have carried away just as much of the essential article after treatment as were actually recovered. In other words, the work was only half completed: the system followed has been unable to give a higher yield owing to errors in its design and construction. Waste recovery as it should be practised to-day is a science. It is just as precise a science as the extraction of nitrogen from the atmosphere, the smelting of steel, or the production of artificial silk. Hit-and-miss methods may have sufficed during the years when commodities were cheap and plentiful, but to-day there is a world-wide stringency in the supply of anything and everything necessary to commerce. As a consequence prices are ruling high, and so the practice of waste recovery along extremely well-defined scientific lines is essential.