SCIENCE SIFTINGS

New Zealand Tablet, 11 April 1918, Page 46

SCIENCE SIFTINGS

By "Volt."

The Invention of "Khaki" Dye. "A business man from Manchester, while travelling in India, happened to fall into conversation with an English officer, who remarked carelessly that the first manufacturer who could produce a cotton drill of khaki color that would not lade, should be able to made a fortune. • "Khaki" is Hindoo for "dust-colored." The khaki cotton has been worn in India by British troops for many years. Its tint was a greenish brown, but it always faded when it was washed with soap. The young business man never forgot the officer's hint. He came home, found a skilful dyer- and with him began the search for- an olive dye which, when used on cotton cloth,-would not yield to soap or soda. They spent years in these experiments, all of 'which proved fruitless. One day they found among several scraps of dyed cloth one which retained its color under the most severe tests. The puzzling fact was that it had been cut from the same piece of cloth and subjected to the same processes as the other scraps, all of which faded. The two experimenters were greatly puzzled, and for months tried in vain to solve the riddle. The one little fragment of khaki was the only one which kept its color against all attacks. , By chance one day they found that the dye in which this scrap had been dipped had remained for some time in a metal dish of a peculiar kind. • The secret was found. The metal of the dish, in combination with the chemicals of the dye, had furnished the one thing needful. They tried the experiment with other pieces. The dye held, and their fortunes were made. It was not chance which gave them .their success, but the indomitable patience and persistence which pursued the chance, and the intelligence which seized it. Novel Bullet-Finder. An electro-magnet which tells the position of a bullet by causing a sound "very like a steamboat whistle" in a stethoscope placed on the patient's skin is one of the recent developments of war surgery, according to Surgeon-General Fotheringham, C.M.G., of the Canadian Army Medical Service. By means of the new magnet the exact position of any elctro-magnetic substance, including the German bullet, can be determined. When the bullet is not deeply seated a vibration is set up by the magnet which can readily be made out by the hand. . , ~ When too deep for this, the electro-magnet is placed on one side of the patient's body and a stethoscope is moved about on the skin opposite the magnet. The steamboat-whistle sound indicates the nearest point to the foreign body, and the skin is marked at that point. The development of the locating of bullets by this magnet and similar means since the war began would be, according to Surgeon-General Fotheringham, perfectly amazing to a civil surgeon. _ -