The Periodic Table Read Online Free PDF

became act. Wasn’t this what Aristotle meant?
    Now, a tube of copper or lead can also be bent, but we soon found out that the red-hot tube of glass possessed a unique virtue: when it had become pliable, you could, by quickly pulling on the two cold ends, pull it into very thin filaments, indeed unimaginably thin, so thin that it was drawn upwards by the current of hot air that rose from the flame. Thin and flexible, like silk. So then silk and cotton too, if obtainable in a massive form, could be as inflexible as glass? Enrico told me that in his grandfather’s town the fishermen take silkworms, when they are already big and ready to form the pupa and, blind and clumsy, try to crawl up on the branches; they grab them, break them in two with their fingers, and pulling on the two stumps obtain a thread of silk, thick and coarse, which they then use as a fishing line. This fact, which I had no hesitation in believing, seemed to me both abominable and fascinating: abominable because of the cruel manner of that death, and the futile use of a natural portent; fascinating because of the straightforward and audacious act of ingenuity it presupposed on the part of its mythical inventor.
    The glass tube could also be blown up; but this was much more difficult. You could close one end of a small tube: then blowing hard from the other end a bubble formed, very beautiful to look at and almost perfectly spherical but with absurdly thin walls. Even the slightest puff of breath in excess and the walls took on the iridescence of a soap bubble, and this was a certain sign of death: the bubble burst with a sharp little snap and its fragments were scattered over the floor with the tenuous rustle of eggshells. In some sense it was a just punishment; glass is glass, and it should not be expected to simulate the behavior of soapy water. If one forced the terms a bit, one could even see an Aesopian lesson in the event.
    After an hour’s struggle with the glass, we were tired and humiliated. We both had inflamed, dry eyes from looking too long at the red-hot glass, frozen feet, and fingers covered with burns. Besides, working with glass is not chemistry: we were in the laboratory with another goal. Our goal was to see with our eyes, to provoke with our hands, at least one of the phenomena which were described so offhandedly in our chemistry textbook. One could, for example, prepare nitrous oxide, which in Sestini and Funaro was still described with the not very proper and unserious term of laughing gas. Would it really be productive of laughter?
    Nitrous oxide is prepared by cautiously heating ammonium nitrate. The latter did not exist in the lab; instead there was ammonia and nitric acid. We mixed them, unable to make any preliminary calculations until we had a neutral litmus reaction, as a result of which the mixture heated up greatly and emitted an abundance of white smoke; then we decided to bring it to a boil to eliminate the water. In a short time the lab was filled with a choking fog, which was not at all laughable; we broke off our attempt, luckily for us, because we did not know what can happen when this explosive salt is heated less than cautiously.
    It was neither simple nor very amusing. I looked around and saw in a corner an ordinary dry battery. Here is something we could do: the electrolysis of water. It was an experiment with a guaranteed result, which I had already executed several times at home. Enrico would not be disappointed.
    I put some water in a beaker, dissolved a pinch of salt in it, turned two empty jam jars upside down in the beaker; then found two rubber-coated copper wires, attached them to the battery’s poles, and fitted the wire ends into the jam jars. A minuscule procession of air bubbles rose from the wire ends: indeed, observing them closely you could see that from the cathode about twice as much gas was being liberated as from the anode. I wrote the well-known equation on the blackboard, and explained to