But one of the most powerful expressions of the possibilities attending the scientific utilization of waste, and one which brings home very forcibly to us the national wealth to be won from refuse, is associated with our woollen industry. Where would Yorkshire be without mungo or shoddy? Dewsbury has become the world’s centre for the disposal of old clothes and woollen rags. Here converge all the streams bearing abandoned flotsam and jetsam into the preparation of which wool has entered. There is scarcely anything more disreputable, if not actually repellent, than a sack of woollen rags. But pass that waste through suitable machines and a wonderful transformation in attractiveness, colouring, and design, as well as texture, is accomplished. Wool can never be worn out. That is an indisputable axiom in woollen circles. It does not matter how many years ago the textile may first have been prepared, nor the many and varied vicissitudes through which it may have passed; it can be used over and over again. It may have travelled through the machines forty or fifty times, may have graced the form of a hundred persons, may have clothed a scarecrow or have been retrieved from a river in the course of its career. True, with each new lease of life it suffers a certain depreciation, but blended with new wool or cotton it is effectively revived. The history of a fibre of wool would be distinctly romantic and thrilling could it be but written, and even the wildest flights of imagination would be unable to rival stern fact. It is the ability to work and re-work up woollen textile for an indefinite period which has contributed to the prosperity of Yorkshire, and which has enabled this country to build up an export trade in this commodity exceeding £500,000,000--$2,500,000,000--a year in value. An impressively successful, yet sinister, utilization of waste was brought to light during the war. In their methodical investigation of the dye-stuffs problem the Germans found it necessary to prepare a certain substance which constitutes the starting-point for the production of one of their leading products. Toluol, a by-product from the manufacture of gas, is taken and treated with nitric acid. Now orthonitrotoluol is the specific product in request, but nitrification produces two substances, orthonitrotoluol and paranitrotoluol, respectively. The last-named is of no use whatever, but its production has to be suffered, though, unfortunately, the yield thereof is twice that of the essential article. So far as the industrial pursuit in question is concerned the paranitrotoluol represented a sheer waste.