THE SAVINGS OF SCIENCE.

Thames Star, Volume IIII, Issue 1748, 10 August 1874, Page 3

THE SAVINGS OF SCIENCE.

(fkom the scibntific ameeican.)

Doubtless many of our readers hare perused Dickens excellent novel " Our Mutual Friend," and hence are, in a measure, familiar with the London dusfheajjs. Perhaps it will be remembered how the great writer describes their contents, and, in his inimitable style, sketches the queer people who often spend their lives among them in seeking for treasures. Those patient searchers ar« creations of the pa9t. Their toilsome occupation .is "gone; for science, with her invention! -and processes, has extended her sway even to the worthless dust heaps,, and from the filthy waste brings out the shining gold. ?she ordinary-waste of a single household -may;"b~eliJMLfirHly'"e"»timated' atr a barrelful per dav%nd London, it-is said, contains five hundred, thousand houses. . Hence the re'a'der'inay" form some idea of the won'defittl'ih'Rennity which contrives to titiiisfo 'the enormous 'aggregate of one hundred -and eighty^ million barrels of r^se itt;the^bw?e;of a single year. , \ Th« local authoritiei of London sell the privilege- 6f removing dust and garbage from each" district to a contractor, who carts it away to a large yard in ihe suburbs^ j^htere hill women, sieve in; hand, separate the mass, by a rude analy-; sisj into component portions.' The most •^ltulble i of the latter are the waste pieces' q^co^l, and the breeze or coal dust and ialf-biirnt ;**hesi ; The amount of waiste^ of'thelatter may be measured by the fact,; that, after selling tha larger pieces to the poor, the refuse breeze is sufficient to bake v the bricks that art rebuilding London.i The material is •by the contactors, t who generally combine the builder's.trade j with thfeir 1 regular calling, for the purpose i otimbedding^the/newly-made bricks into-. compact squares. ■■; The coal dust having; been fired, the mass burns with slow. combustion 5 for two or three weeks;' aided; , by the circtilationbf air which is kept upi by the-method of stacking. The other, constituentsi of the> dust-heap are sepcra- = ted'byv-the sifters 'with the utmost ra-; pidtiy.:'bones, ragi, paper, old iron, glass and broken crockery, and even bread^ as they are eliminattd from the mass, being piled in separate heaps. The benes are put to a «cor« of different uses. Of the several tons of bones that are picked out of the dust in the course of a week, some go immediately, to the boiling houses, where every' portion of fat and gelatine they can yield is. extracted; the former ■übstance is bought by the soapmaker, the latter it utilised to make the patent •preparations employed in cookery, photography, &o. The larger bones are used By th« turners and are converted into hundreds of ni,c-nacks; so that the bone you may have picked at dinner again enters your mouth, after many changes, as a -toothpick or toothbrush, while the ■mailer pieces, for aught you know, have been calcined, and form the very charcoal tooth-powder on your toilet table. Fragments that 1 cannot otherwise be employed are ground very fine, and treated with sulphuric acid, constituting an excellent artificial fertiliser. Bone dust is also sometimes uced by bakers for purposes of adulteration, so that the poetical remark of the giant in the fairy tale, -" I'll- grind hit bones to mak* my bread," is fulfilled both figuratively and literally. Another important product extracted from bones is phosphorous, for which there are an endless number of uses; and, finally, the fat which is saved in the process of boiling is employed to make the commoner kinds of soap. Scraps of paper abound in the dust heaps. There are carefully sorted, the white from the coloured md the printed. The soiled pieces, which/cannot, be profitably re-manufactured,^re used to make papier mache ornamenjd; dolls' heads, &c.; the clean paper is returned to the mill, and even the printed paper has the ink discharged from it, and goes again into circulation., Old rags, of course, are valuable to the papermaker, although the discovery of other materials renders | this form of waste not quite ao important as formerly. Greasy dishcloths cannot §o to the mill again, so they are sent to , le hop-grower, to whom they are valuable as fertilisers. Woollen rags, if they happen to be dyed scarlet, are treated for | the recovery of their cochineal, which is used as^ r dyeing material; and other valuable coloured rags are ground up to make flock paper. •The .great market for all oldwoollen , fabrics, in England is the town of Batley and its neighborhood, in lorkshire, the , great shoddy metropolis. A writer lays, regarding this manufacture : " Reduced to filaments and greasy pulp, by mighty toothed cylinders, the much-vexed fabric re-entera life.in the most brilliant forms, from the, solid pilot'cloth to silky mohairs < •sjpl glossiest tweeds." . , Cotton 'and woollen rags are both Ttluable when separate, but of late years it has be.en the custom to weave the cotton Mid woollen together, the warp being made of the latter material, and the weft of the former ; thu» mixed, however, the fabric cannot be converted into paper or cloth. '■ Many endeavors have been made to effect'a separation, and at present the rags are placed,in ; a,closed receiver and subjected "to steam at a very high temperafareP • The result is that the cotton comes out pure and fit for the paper maker; the wool is reduced to a dark brown powder known as the ulmate of ammonia,- 'and' is employed to enrich manures which are poor in nitrogen. "A very important constituent of the dust heap is the old iron, battered saucepans, old pails, rusty hoops,- horse-shoes, &nd nails from the road. All soldered artidet have the solder extracted from them, as it is more valuable than the iron, and the cheaper metal is then melted. The nails are not mixed ; with the common cast iron, as they are much •ought after by gunmakers for the [purpose of stub twist barrels. • Scraps of iron* it is found, may be made very use-

ful in securing the copper in the streams washing veins of copper pyrites. Pieces of battered iron are placed in tanks, into which thes* are collected; the copper quickly incrusts the iron, and in process of time entirely dissolves it, so that a mass of copper takes the place of the iron.' The, residuum, in the shape of a colored deposit, is at times taken out, dried, and snjqlted.

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