This point having been established, M. Curie proceeded to the most sensational part of his demonstration, by closing the stop-cock F and then placing the lower bulb B, still radiant, in a vessel G containing liquid air, the result being that the light in the bulb B gradually grew stronger while the light in the bulb A diminished, until, presently, _all_ the light seemed concentrated in B and gone from A, the conclusion being that the intense cold of liquid air had produced some change in the emanations, had possibly reduced them from a gas to a liquid, thus withdrawing them from A to B and checking the one glow while increasing the other. In talking with Sir William Crookes, M. Curie was interested to learn that the English scientist had just devised a curious little instrument which he has named the spinthariscope, and which allows one to actually _see_ the emanations from radium and to realize as never before the extraordinary atomic disintegration that is going on ceaselessly in this strange metal. The spinthariscope is a small microscope that allows one to look at a tiny fragment of radium, about one-twentieth of a milligramme, supported on a little wire over a screen spread with sulphide of zinc. The experiment must be made in a darkened room after the eye has gradually acquired its greatest sensitiveness to light. To the eye thus sensitive and looking intently through the lenses the screen appears like a heaven of flashing meteors, among which stars shine forth suddenly and die away. Near the central radium speck the fire shower is most brilliant, while towards the rim of the circle it grows fainter. And this goes on continuously as the metal throws off its emanations; these myriad bursting blazing stars _are_ the emanations--at least, we may assume it--and become visible as the scattered radium dust or radium vapour impinges speck by speck upon the screen, which, for each tiny fragment, flashes back a responsive phosphorescence. M. Curie spoke of this vision, that was really contained within the area of a two-cent piece, as one of the most beautiful and impressive he had ever witnessed; it was as if he had been allowed to assist at the birth of a universe or at the death of a molecule. Dwelling upon the extreme attenuation of these radium emanations, M. Curie mentioned a recent experiment, in which he had used a platinum box pierced by two holes so extremely small that the box would retain a vacuum, yet not small enough to resist the passage of radium emanations.