SCIENCE SIFTINGS

New Zealand Tablet, Volume LI, Issue 36, 3 September 1924, Page 54

SCIENCE SIFTINGS

By "VOLT"

COLOR PROBLEMS. Science Baffled by the Peacock's Wonderful Tail. Few people have the smallest knowledge of the debt our modern civilisation owes to chemistry. Thirty eminent men of science have accordingly combined to enlighten as far as possible popular ignorance on the subject, and the Tesult is Chemistry in the Twentieth Century, edited by Dr. E. F. Armstrong, F.R.S. The chief impression which remains with, the layman after reading the book is that every day, in every way (says T.P.'s and Cassell's Weekly), we are being more and more dominated by the discoveries of the chemist. Every improvement in, social amenities, in the nation's health, in our comforts, and our luxuries— appear to depend in the last resort on the work done in the chemist's laboratory. But we are an ungrateful lot, and we give no thanks for the blessings bestowed on us by the chemist. Nor do the majority of us pay much attention to him when he is explaining the wonders of nature. For the chemist explains as well as discovers. He can tell us for instance, why one person's eyesare blue and another's black, what makes the gorgeous ■ colors of a sunset and the iridescent splendor of a peocock's • tail. There is a mystery, however, about a peacock's tail - , which even science cannot solve. "The differences of color and graduations of effect upon a single feather are due," ■we are told, "to slight variations in the thickness of the* color-producing laminae." But the astonishing point is that though a minute difference in the thickness will alter the colors entirely, the same general types of colored feathers are produced generation after generation with marvellous exactitude. Why should this be so? Nobody knows. So far as color is concerned, the most practical work: done by chemistry is in the dye industry. The discovery of how to utilise coal-tar for dyeing has often been told,, and over a thousand dyes are now obtained by chemical reactions from that once-despised waste product. But it is surprising, if not disconcerting, to read that" thousands of years ago an extraordinarily wide range of shades could be obtained I>y the skilled dyer, many being of great beauty and some possessing durability comparable with the best obtainable by the modern dyer." In fact, the chief disadvantage which the ancient Egyptian dyer labored under was the extreme length and. tediousness of the processes he employed, which, after all, was no great matter in a day when there were no hustlers.. Indeed, if one were inclined to be cynical, it might beasked whether the scientific progress of which we are justly so proud has really added anything to the sum of humane bappiness. Fruit All the Year Round. As a result of a long series of scientific experiments it has been found possible to preserve fruit of all kinds for several months without cooking it. Pineapples from the West Indies, grapes from South Africa, and peaches from California, if packed by this new method, will arrive in London just as fresh as when packed. Dried fruit, too, can be preserved in such a manner that, when water is applied on arrival, the fruit regains all itfc original flavor and size.: # The preserving apparatus is simple and cheap. The fruit is washed and packed into tin cans. A light sugar syrup is then added, and all air is excluded. The tins are then hermetically sealed and stored in refrigerators. On. arrival at 'the port of destination the frozen fruit is thawed - out, when it immediately becomes as fresh as it was before packing. _. • Grapes are preserved by placing the bunches in tins, into which sulphuric acid gas is pumped. 0 When all air is excluded the gas tube is withdrawn arid the tins are sealed up. The sulphuric acid kills the germs which attack the grape-skins, and .so preserves the fruit until-required for. use. ■.,;■•