NATURAL RIVER OF INK FORMED BY STREAMS.

Star (Christchurch), Issue 18959, 4 January 1930, Page 11

NATURAL RIVER OF INK FORMED BY STREAMS.

In a part of Algeria is a river of ink formed by the union of two streams. The water of one is impregnated with iron, and the other, which drams a great swamp, with gallic acid. Nature, acting as a chemist, unites the combination of iron and acid, and the result is a true ink, with which one can write letters. Probably no product in the world is made from a greater variety of raw materials than* ink. For centuries past the best grades of writing ink have been made from a certain species of nut galls found in Asia Minor. The gall fly, a small wasplike insect, burrows into soft twigs and deposits her eggs. A lump, sometimes over an inch in diameter, is formed, called a gall. It contains a large amount of tannin, which is the basic substance of inks. Other ink is made from logwood from the West Indies, or by mixing green vitriol with other tannin solutions. Fountain pen ink is usually made from the black aniline dye, nigrosen. All colours of inks arc made with aniline dyes. Then there is the secret of “sympathetic” inks, which leave no visible marks on the paper when they are used. Some of the favourite secret inks are lead acetate solution, whose invisible marks turn black upon exposure to sulphurated hydrogen: cobalt nitrate solution, which turns blue when treated with oxalic acid, and cobalt chloride or nitrochloride, which becomes green when heated.