"No; it keeps the form of small white crystals, which may be crushed into a white powder, and which look like ordinary salt. See, here are some." He took from the table drawer a small glass tube, not much larger than a thick match. It was sealed at both ends and partly covered with a fold of lead. Inside the tube I could see a white powder. "Why is the tube wrapped with lead?" I inquired. "For the protection of those who handle it. Lead stops the harmful rays, that would otherwise make trouble." "Trouble?" "Yes; you see the radium in this tube is very active; it has an intensity of 1,500,000, and if I were to lay it against your hand or any part of your body, so"--he touched my hand with the bare tube--"and if I were to leave it there for a few minutes, you would certainly hear from it later." "But I feel nothing." "Of course not; neither did I feel anything when I touched some radium here," and pulling up his sleeve he showed me a forearm scarred and reddened from fresh-healed sores. "But you see what it did, and it was much less intense than this specimen." He then mentioned an experience of his friend, Professor Becquerel, discoverer of the "Becquerel rays" of uranium, and in a way the parent-discoverer of radium, since the latter discovery grew out of the former. It seems that Professor Becquerel, in journeying to London, carried in his waistcoat pocket a small tube of radium to be used in a lecture there. Nothing happened at the time, but about a fortnight later the professor observed that the skin under his pocket was beginning to redden and fall away, and finally a deep and painful sore formed there and remained for weeks before healing. A peculiar feature of these radium sores is that they do not appear for some considerable time after exposure to the rays. "Then radium is an element of destruction?" I remarked. "Undoubtedly it has a power of destruction, but that power may be tempered or controlled, for instance, by this covering of lead. M. Danysz, at the Pasteur Institute, will give you the pathological facts better than I can." This brought us back to physical facts, and I asked M. Curie if the radium before us was at that moment giving out heat and light, for I could perceive neither. "Of course it is," he replied. "I will take you into a dark room presently and let you see the light for yourself. As for the heat, a thermometer would show that this tube of radium is 2·7 degrees F. warmer than the surrounding air." "Is it always that much warmer?" "Always--so far as we know. I may put it more simply by saying that a given quantity of radium will melt its own weight of ice every hour." "For ever?" He smiled. "So far as we know--for ever. Or, again, that a given quantity of radium throws out as much heat in eighty hours as an equal weight of coal would throw out if burned to complete combustion in one hour." "Suppose you had a considerable quantity of radium," I suggested, "say twenty pounds, or a hundred pounds?"