The marvels of radium may be said to have been more or less foreshadowed by the discovery of the Roentgen rays. It was immediately determined that the emanations of a Crookes tube were not ethereal undulations such as ordinary light, but that they consisted of actual material particles of matter highly charged with electricity. Naturally the attempt was made to discover whether the phenomena of phosphorescent substances were not akin to those of the Crookes tube. The leading spirit in this movement was Professor Henri Becquerel, who selected the metal uranium as the subject of his experiments. He accidentally discovered that the so-called phosphorescent attributes of uranium were not due to the absorption of sunlight, but that the substance was spontaneously active, and that the light which came from radium was a new kind of emanation entirely different from the X-rays. To these new radiations the name "Becquerel Rays" was given.

Uranium is obtained from pitchblende, an ore more or less widely distributed about the world, but found chiefly in Bohemia and in Cornwall. Madame Curie, who, at the time Becquerel was making his investigations, was a senior student at the Municipal School of Physics and Technical Chemistry in Paris, had selected "Radio-Activity" - a name which she coined - as the subject of her Doctor's thesis. Naturally it was necessary for her to study uranium and similar minerals with some care. She found that, after having extracted all the uranium contained in her specimen of pitchblende, there still remained in the residue a substance far more active than uranium. After isolating this unknown radiant substance and analyzing it, she found that it contained two new elements. The one she christened "polonium," after Poland, the land of her birth; the other she named "radium."

Several tons of pitchblende must be treated and concentrated before a few grains of radium are obtained. But those few grains are worth more than any precious gem or metal in the world. Indeed they have almost any value which their fortunate possessor may choose to give them. There are probably not two pounds of pure radium in existence; but at the present market price they would be worth each about three and one-half million dollars. There is more gold in sea water than radium in pitchblende; and that is why its price is so high.

The properties of radium will probably necessitate a decided revision in some time-honored chemical theories; for radium refuses to conform to our long-established atomic theories, and behaves in a most inexplicable fashion. In the first place the radio-activity of the element has been found to consist of three distinct sets of emanations, which have been respectively christened the Alpha, the Beta, and the Gamma rays, for want of better names.

The Alpha rays are not, like ordinary light, ethereal pulsations, but actual material particles hurled off at a speed of about 20,000 miles per second from the parent mass. They are highly charged with positive electricity. Their speed is about 40,000 times greater than that of a rifle bullet.

The Beta rays, which consist of particles of matter, corpuscles of electricity or "electrons" as the modern physicist calls them, move still more swiftly. Each of the Beta particles (very much smaller in size than the Alpha particles) travels at the rate of about 100,000 miles a second. They are the fastest moving objects known in the universe; for their speed is three hundred times faster than that of the swiftest star. Such is their velocity that it takes a foot of solid iron to stop them.

The Gamma rays are probably Roentgen rays, if one may judge by the similarity of the properties of the two. Like the Beta rays, the Gamma emanations have remarkable penetrating properties. But of the three kinds of rays discharged by radium, the Gamma rays are the most difficult to detect and the least perfectly understood.

Professor Curie, Madame Curia's husband, has discovered that radium constantly maintains a temperature of about five or six degrees above the surrounding atmosphere. For some time this startling phenomenon baffled physicists. Here was a substance constantly giving off heat without being apparently consumed, and without anything to make it hot. It is now thought that this strange property can be explained by assuming that the particles collide with one another, and that the heat generated by the impact (a heat that must be very marked when it is considered how enormous is the energy of a particle moving at the rate of many thousand miles a second) is sufficient to explain the heat generated by radium.

The fact that radium is a spontaneous source of thermal energy is in itself a fact sufficiently startling. Sir William Ramsay, however, has discovered still other startling properties of this startling substance. He collected the material particles which are shot from the substance, analyzed them, and found that after a few days they changed into helium, a gas which was first discovered burning in the sun. This seems dangerously like the transmutation of one element into another, the problem on the solution of which the medieval alchemist had worked for centuries. After ages of labor seventy-odd bits of primordial matter had been wrung from the earth, so simple and so unchangeable in their nature that they were deemed elements. And now one of them proves to be nothing but the product of another. Can we ever be certain again that the rest are not also likely to change? Is it any wonder that our chemistry needs revision?

The atomic weight of radium has been ascertained by Madame Curie to be 225; that of helium is 2.2. In other words, every atom of radium breaks up into about 100 parts of helium. What becomes of the old teaching that atoms are indivisible particles of matter? Some of the more advanced thinkers have abandoned the atom and adopted the "electron" as the ultimate unit. The atom is certainly quite inadequate to account for the properties of radium. Atoms may be said to be composed of electrons moving, like miniature solar systems, with inconceivable rapidity in well-defined orbits. Sometimes a little planet of that system becomes unstable, darts off with terrific speed like a comet, and thus gives rise to the phenomena of radium, of uranium, and of every other radioactive substance.

Has radium any practical value? it may be asked. So far it is more of a scientific curiosity than anything else. Still, it is not without some use. It is an excellent detector of false diamonds; for it causes the real gem to glow with wonderful brilliancy, while the paste imitation is left comparatively lusterless. Then, again, radium kills bacteria and even very small animals. The modern physician has used the substance with some success in treating certain diseases, among them cancer and lupus. Living tissues of the body are strangely affected by short exposures to the substance. Sores are produced, like burns, which heal only after weeks have elapsed. An electroscope has also been invented, the underlying principle of which is dependent upon the properties of radium.