"BLACK PHOSPHORUS" HAD ORIGIN IN HARVARD LAB.

Despite inadequate equipment, which the recent drive for $10,000,000 will try to remedy, the University's chemistry department has made several important discoveries during the past few years. One of the most noteworthy of these was the location of "black" phosphorus.

For many years the Red and White members of the phosphorus family have been well known. A new member has now joined the group--Black, according to Professor P. W. Bridgman '04, Professor of Physics in the University. Phosphorus means "light- bearer" and most of us have seen the glow which the old-fashioned "all-day choker" matches gave out when scratched in the dark. This pale glow is due to white phosphorus used in making the head of the match so that it will strike easily and anywhere--from the thumb nail to the trouser leg.

Unfortunately the same chemical activity that makes white phosphorus glow in the dark also makes it poison the workmen in the factories and occasionally kill a mouse or an inquiring baby, so that matches of this sort were practically taxed out of existence by Federal law some years ago.

Nowadays the chemists have found other materials to take the place of white phosphorus, so that the "strike- anywhere" match has become a fairly digestible article. White phosphorus still finds use, however, to improve the vacuum in electric lamps, in making rat poisons, and, in smoke screens, for when a shell filled with it bursts, the phosphorus catches fire instantly and sprays its flaming drops in every direction, sending up a cloud of dense white smoke.

A better kind of phosphorus for matches is the red variety, which is used on the box in making safety matches, and catches fire if you rub it hard enough with the powdered glass and active chemicals in the head of the match. This is a mild-mannered, quiet sort of a substance, it doesn't catch fire in the air until you heat it quite hot, it won't dissolve in anything, and it can be eaten without any discomfort.

A third form of the element, known as black phosphorus, was discovered in 1910 at Harvard University by Professor Bridgman, who was studying the effects of high pressure.

A really deep diver must wear a metal helmet, and either a specially-built rigid suit or else get used to one or two atmospheres excess air pressure in his breathing supply. A heavy tire may need a pressure of 100 lbs, which is not quite seven atmospheres.

These examples may give some idea of the range of Professor Bridgman's work, which begins at 3000 atmospheres and goes up to 14,000--the highest ever reached by experiment. At this pressure mercury and hydrogen pass through thick nickel steel as though it were a sieve; and there are six different kinds of ice instead of the one that used to be found in cocktails. At these pressures it was found that white phosphorus when heated to 390 degrees suddenly changed from a colorless, waxy, translucent material to a much denser, jet-black, flaky substance like the graphite or black "lead" used in lead pencils. This is an absolutely new form of the element, with properties all its own and with a smaller chemical activity even than red phosphorus. Chemists at Harvard are studying the properties of the new form with a view to finding out whether its novel properties make it especially useful for any purpose.

The foregoing is an illustration of how the use of up-to-date scientific equipment often results in quite unexpected discoveries. The physical laboratory at Harvard, where this work was done, is fairly modern and well equipped. When the new chemical laboratories are built, for which Bishop Lawrence is now raising the money, great advances in the chemical field may also be expected.