RUBBISH.

Otago Witness, Issue 3396, 16 April 1919, Page 59

RUBBISH.

By Doxa Foy, in Chambers's Journal

It is often said that the waste of one generation proves the wealth of the next. One wonders how our own "next generation" will fare, as we are leaving very little "waste" for them to turn to account. The most unpromising materials are being made to yield products of great value, and some of these are so accessible, so easily and economically manufactured, that the development of them is likely to be continued, now the war is over. The task of "making bricks without straw" has not proved beyond' 'us, and it may be that our task-masters, -Scarcity and Necessity, will, unlike those of the Hebrews in Egypt, one day be the recipients of our deepest gratitude. Our Victorian grandmothers are often referred to as examples of thrift, but we imagine they would have_ been somewhat surprised if they had been asked to save from the rubbish heap their old boots, the "Combings" of their pet dogs, their plumi stones, and nut shells ! It was considered something of an act of supererogation to save the bones of the joint for soup, instead of throwing them to the dog; and yet we are told nowadays that these bones will provide 80 'different by-products, after the cook—and perhaps the dog too !—is done with them ! It will be many years before living becomes easv again, and it may be that we shall never go back to the extravagant, wasteful methods which had grown up with this luxury-loving generation. Be that as it may, it is probable that the development of some of these newly discovered industries will do something towards providing work for the "unemployed" after the war. At the best of times the problem of fuel has been a source of anxiety to the poor, and one hopes that the substitute for coal, which even at this time costs under ten shillings a ton to prepare, will not be allowed to slip into abeyance. This substitute is made from pulverised ash-bin refuse, of which ten million tons a year are said to be produced in England. It burns with a good flame, emits very little smoke, and gives out a strong heat. Straw is now being made to yield most of the substances obtained from coal. Special retorts have been invented for the distillation. The straw is pressed into cubes and heated to about lOOOdeg. F.— five times as hot as boiling water! By this means a ton of straw produces, in something less than an hour, nearly twelve thousand cubic . feet of gas, . six hundred pounds of lampblack, eight gallons of tar, and a large amount of ammonia >for fertilising purposes.

Sawdust has hitherto been regarded as a convenient material' for packing, but very little use has otherwise been made of "it. In the near future, when the demand for small and cheap houses has to be met, sawdust is likely to be exalted to a high place in commercial value. Mixed with clay, it is being made into bricks and tiles, the beauty of which is that they can be cut with a saw, and nails can be driven into them with ease. Indeed, we may expect the whole house to be built of sawdust, for, when mixed with concrete and laid down moist, _ it makes an excellent flooring material, softer and more elastic to the tread than either ordinary concrete or tiles. The rubbish heap has been the source of many romances in the history of commerce. The despised but necessary "dust .heap" has proved again and again that nothing is ' waste." , . Rubbish heaps are like men, in that some are born great, some achieve greatness, and some have greatness thrust upon them. Among the inherently great were the disfiguring mountains of rubbish which used to surround steelworks, composed of the old and useless linings of the vessels in which the steel was made. They were a veritable nightmare to the manufacturers, till it was suggested that the materials of which the linings were made might prove more valuable on the land as" fertilisers. Now the demand for "basic slag," as it is called, exceeds the supply I Among the rubbish heaps which have, in spite of many obstacles, "achieved greatness" may be mentioned those composed of the refuse known as "silk waste." As all who have kept silkworms are aware, this "waste," of old cocoons, dead silkworms, and a sticky mass of twigs and leaves, presents a most unpromising material on which to work. Nevertheless, Mr Samuel Cunliffe Lister, a woollen manufacturer, afterwards Lord

Masham, succeeded in turnirfg this loathsome mess into fabrics of groat beauty and daintiness, after many trials and failures—incidentally making for himself a huge fortune thereby. Ae an instance of waste "which has had "greatness thrust upon it"" ("notoriety" would perhaps be a better word), hydrochloric acid, from which chlorine gas ia made, may be .cited. At the end of the eighteenth century a Frenchman, M. Leblanc, .invented a process for making soda from common salt. By this process hydrochloric acid was given, off as a waste product. We in these daya know only too well the cruel and desolating properties of this gas. Not realising that the#gas was heavier than air, the manufacturers thought to I dispose of it by letting it escape through tall chimneys, with the result that all vegetation was destroyed, and life became | almost impossible in largo areas round the factories. Taller chimneys were built —with the consequence that larger areas were affected. Then some one hit upon the idea of dissolving the hydrochloric acid i in water. This water, of course, ultimately reached the rivers, and the outcry increased. The manufacturers were at their wits' .

end, when the problem was solved in a remarkable manner, and the hydrochloric acid became a valued source of wealth instead of an unmitigated nuisance. .In 1861 the ; duty on paper was abolished, with the result that a great) demand grew up for books and newspapers. (Straw, grass, nettles, wood, and other materials were used for the manu* : facture of paper, and these must, o| necessity, be bleached in some way. Chlorine gas was then, as now, the best i and cheapest bleaching agent known, and it was not long before the hated hydrochloric acid became a valuable and valued by-product. A present day instance, which repeats the history of basic slag, is that _of the ' waste heaps surrounding the Cornish tinmines. The metal tungsten, used for hardening steel, is obtained from wolfram, an ofe which is found associated with tin. Wolfram used to be regarded as a veritable "wolf in the fold" by the tin miners. As "it was of the same specific gravity as tin, the only meana of separating it was by hand. When war broke out wolfram leapt into prominence as one of the most precious ores in the world, and the rubbish heaps around the Cornish tin mines became a valuable source of supply. Whereas the smelters once demanded that the tin should not contain more than 2 per cent, of wolfram, > now the position is reversed, and the . wolfram must not contain more than 2: per cent, of tin.