SCIENTIFIC MARVELS OF A CHEMICAL AGE

Dominion, Volume 30, Issue 261, 31 July 1937, Page 6 (Supplement)

SCIENTIFIC MARVELS OF A CHEMICAL AGE

Wonders Out Of Wood And Cotton

If you look upon wood as wood, ami coal as coal, you are living half a century behind the times, says a writer in a scientific journal. To modern lite wood is cellulose, and as such responsible foi- many fine and valuable substances ; coal may be fuel, dyes, or perfume, according to the needs of the moment.’ And this because the world has hurtled suddenly into a chemical age. Take cellulose, the modern miracle discovery, which is really the libije of wood. Let the scientist treat it with nitric and sulphuric acid, and he gets the basic ingredient of smokeless powder. Nitro-cellulose dissolves in many solvents, and gives viscous solutions, which, when spread in thin layers while the solvent evaporates, becomes transformed into a transparent, flexible film. That thin, transparent, flexible film has revolutionised the motoring industry. A few years ago cars were finished with coat upon coat of slow-drying paints, enamels and varnishes. A car stayed in the paintshop for (lays and weeks. Now a quick, long-lasting lacquer reduces the finishing time from days to hours. This amazing substance, which et.n be a high explosive at the chemist’s whim is still more versatile. By covering cloth with lacquer an American firm produces an impervious fabric which can be made to simulate the hide of any animal or the skins of reptiles. This material, used as “fabrikoid,” is used for everything—book-binding to travelling bags, brief cases,’tablecloths which look like damask but are soilproof, durable wall-covering, furniture upholstery, coated fabrics for automobiles. window shades which can be washed with soap and water, men's belts, parts for shoes, and scores of other products.

Blend camphor with nitro-cellulose and you get another material of a thousand uses, not a lacquer, but a plastic—"Pyralin.” When heated, this plastic can be worked like bread dough and it is produced in rods, sheets and tubes and in all the hues of the rainbow, It forms the “sandwich” between two sheets of shatter-proof glass, it is made into toilet articles of beauty and durability, tooth-brush handles, advertising novelties, bath fixtures, fountainpen barrels, toys, automobile trim and articles of office equipment. The elephant am! the tortoise should be grateful to the chemist, because this inexpensive plastic in its myriad hues gives the beauty, durability, and lasting loveliness, of ivory tusks and tortoise shells. “Pyralin” is tough, hard, solid, almost unbreakable, and can be cut, sawed, filed, blown, rolled, planed, hammered, drilled, turned in lathes, without cracking or splintering. Its surface can be dull or lustrous, smooth or rough; it can be transparent or opaque; it can be given any flat colour or mottled. It lends itself to exact simulation of mother-of-pearl, ivory, ebony, and other natural substances. Its uses are legion in everyday life. Think back again to cellulose, the base of all these products. Instead of treating it with nitric and sulphuric acid to produce nitro-cellulose, try caustic soda—lye to you. You now obtain —not nitro-cellulose, but a syrupy solution, known as viscose. Now'extrude this syrup through a narrow slit and into a bath, of sul-

phuric acid —sulphur plus water plus air—and you get not a viscous solution, but a solid—a cellulose film. You know this film as “Cellophane”—the transparent shimmery, flexible, moisture-proof wrapper which protects nearly everything you buy. It is used for decorative purposes in the arts and crafts; it is made into rain capes and used in colours on hats, shoes and belts and for printing purposes.

Now watch closely while the chemist performs another sleight-of-hand trick. Instead of extruding the syrup through a slit and into an acid bath, he merely squirts it through tiny holes, called spinnerets, and into the acid. And it emerges not as a film, but as a filament microscopic threads finer than human hairs, finer even than the silk ot the silk-worm. Here you see the birth of rayon, the first man-made fabric. So line are the tiny strands that one pound of them would reach from the Atlantic to the Pacific, but when woven into a yard, it can be converted into a fabric of chalky crepe or transparent velvet, dull or lustrous, in solid colours or printed designs. Man at last has succeeded in doing mechanically what the silkworm does —making a filament ftoni a plant. Tlie difference is that man uses sjiruce wood or cotton and wotks under scientifically controlled conditions, the silkworm takes the mulberry leaves as they come. Moreover, the natural silk filament is a protein material, not cellulose.

In many minds rayon is associated only with cheap and inferior goods, but such is not tlie case to-day. The strength and uniformity of rayon yarn have been improved to a point where it is claimed that rayon as irregular as tlie most regular natural yarns/available would be unsalable to-day. It is also true that more brilliant colour effects can be achieved with rayon than with other fabrics because its lustre in itself gives added brilliance.

Various other products besides rayon and Cellophane are produced from viscose Put the syrup into a vat with chemical solids, stir it up and then dump it into the acid bath and it “freezes.” Treat the coagulated product to remove the chemicals, thus creating holes where the chemical was—and you have a sponge. Saw up this product and you obtain a sponge of regular shape in 'any size desired. Sausage casings and bottle caps also are made from the same syrup.

Now let’s return once more to our starting point—cellulose. Treat this cellulose with acetic acid—which gives vinegar its taste —and you obtain, not nitro-cellulose and not viscose, but cellulose acetate aud the starting point for a new array of products. Like nitro-cel-lulose, it dissolves in solvents to form viscous solution, but its solubility characteristics are different. One of its characteristics is that it is slow-burn-ing and hard to ignite, so it can be used to make products employed where fire would be a hazard. It goes into photographic film and safety film for movies, and as a thin plastic sheet reinforced with wire mesh it is used instead of glass in poultry houses because it admits ultra-violet light.

It is worked into a plastic somewhat like “pyralin” and it is made into a fabric, acetate rayon and converted into high-style women’s wear.