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Uncle Tungsten
p158 Electrochemical attraction, for Davy, was the attraction of opposites -- the attraction, for example, of an intensely “positive” metallic ion, a cation like that of sodium, to an intensely “negative” one, an anion like that of chloride. But most elements, he thought, came between these on a continuous scale of electro-positivity or -negativity. The degree of electropositivity among metals went with their chemical reactivity, hence their ability to reduce or replace less positive elements.
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p160 I did not realize at first that there was any connection between these experiments [adding metallic coatings, or “trees” to a material like zinc by placing it in solutions of various metallic salts, removing tarnish from silver spoons, electroplating various household items with chromium] and the batteries I was playing with at the same time, although I thought it an odd coincidence that the first pair of metals I used, zinc and copper, could produce either a tree or, in a battery, an electric current... I started to realize that the two series -- the “tree” series and [Alessandro] Volta’s series -- were probably the same, that chemical activity and electrical potential were in some sense the same phenomenon.
We had a large old-fashioned battery, a wet cell, in the kitchen, hooked up to an electric bell... it contained an earthenware tube with a massive, gleaming copper cylinder in the middle, immersed in a bluish liquid; all this inside an outer glass casing, also filled with fluid, and containing a slimmer bar of zinc. This Daniell cell... had a thoroughly nineteenth-century, Victorian look about it, and this extraordinary object was making electricity all by itself -- not by rubbing or friction, but by virtue of its own chemical reactions. That this was... a radically different sort of electricity, must have seemed astounding in the extreme, a new force of nature, when Volta discovered it in 1800... now one could have at one’s disposal a steady, uniform, unvarying current. One only needed two different metals -- copper and zinc would do, or copper and silver (Volta worked out a whole series of metals, differing in the “voltage,” the potential difference, between them), immersed in a conducting medium.
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p163 ...Static electricity could generate great sparks and high-voltage charges (a Wimshurst machine could generate 100,000 volts), but very little power, at least to electrolyze. And the opposite was so with the massive power, but low voltage, of a chemical cell.
I poked around in Wiki for a bit but couldn't find anything that made this more understandable.
If the electric battery was my introduction to the inseparable relation of electricity to chemistry, the electric bell was my introduction to the inseparable relation of electricity to magnetism -- a relation by no means self-evident or transparent, and one that was discovered only in the 1820s.
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p165 [Michael] Faraday, who in 1821 designed this apparatus [to show that there was a magnetic field around a magnet] -- in effect, the world’s first electric motor -- immediately wondered about its reverse, if electricity could produce magnetism so easily, could a magnetic force produce electricity? Remarkably, it took him several years to answer this question, for the answer was not simple. Putting a permanent magnet inside a coil of wire did not generate any electricity; one had to move the bar in and out, and only then was a current generated... It took even a genius like Faraday ten years to make the mental leap... that movement was of the essence. (Movement, Faraday thought, generated electricity by cutting the magnetic lines of force.) Faraday’s in-and-out magnet was the world’s first dynamo -- an electric motor in reverse.
p166 ... Electric motors were taken up and developed almost at once, so that there were battery-powered electric riverboats by 1839, while dynamos were much slower to develop and became widespread only in the 1880s... Nothing like these vast, humming dynamos, weaving a mysterious and invisible new power out of thin air, had ever been seen, and the early powerhouses... inspired a sense of awe. (This is evoked in H. G. Wells’s early story “The Lord of the Dynamos,” in which a primitive man begins to see the massive dynamo he looks after as a god who demands a human sacrifice.)
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Magnetism and electricity had seemed at first completely separate; now they seemed to be linked, somehow, by motion. It was at this point that I turned to my “physics” uncle, Uncle Abe, who explained that the relationship between electricity and magnetism (and the relationship of both to light) had indeed been made clear by the great Scottish physicist Clerk Maxwell. A moving electrical field would induce a magnetic field near it, and this in turn would induce a second electrical field, and this another magnetic field, and so on. With these almost instantaneous mutual inductions, Maxwell envisioned, there would be, in effect, a combined electromagnetic field in extremely rapid oscillation, and this would expand in all directions, propagating itself as a wave motion through space. In 1865, Maxwell was able to calculate that such fields would propagate at 300,000 kilometers per second, a velocity extremely close to that of light [c]. This was very startling -- no one had suspected any relationship between magnetism and light; indeed, no one had any idea what light might be, although it was well understood that it was propagated as a wave. Now Maxwell suggested that light and magnetism were “affections of the same substance, and that light is an electromagnetic disturbance propagated through the field according to electromagnetic laws.” After hearing this, I began to think of light differently -- as electric and magnetic fields leapfrogging over each other with lightning speed, braiding themselves together to form a ray of light.
If only I had had uncles who excelled at chemistry and physics instead of farm equipment and pellet guns.
p168 It followed, as a corollary, that any varying electric or magnetic field could give rise to an electromagnetic wave propagating in all directions. It was this, Abe said, that inspired Heinrich Hertz to look for other electromagnetic waves -- waves, perhaps, with a much longer wavelength than visible light. He was able to do this, in 1886, by using a simple induction coil as a “transmitter” and small coils of wire with tiny (a hundredth of a millimeter) spark gaps as “receivers.”When the induction coil was set to sparking, he could observe, in the darkness of his lab, tiny secondary sparks in the small coils. [See HERE] “You switch on the wireless,” said Abe, “and you never think of the wonder of what’s actually happening. Think how it must have seemed on that day in 1886 when Hertz saw these sparks in the darkness and realized that Maxwell was right, and that something like light, an electromagnetic wave, was raying out from his induction coil in every direction.”
Hertz died as a very young man, and never knew that his discovery was to revolutionize the world. Uncle Abe himself was only eighteen when [Guglielmo] Marconi first transmitted radio signals across the English Channel, and he remembered the excitement of this, even greater than the excitement over the discovery of X-rays two years earlier. Radio signals could be picked up by certain crystals, especially crystals of galena; one would have to find the right spot on their surface by exploring them with a tungsten wire, a “cat’s whisker.” One of Uncle Abe’s own early inventions was to make a synthetic crystal that worked even better than galena. Everyone still spoke of radio waves as “Hertzian waves” at this point, and Abe had called his crystal Hertzite.
This is where you would throw in the towel and give up on the improbability of this story if it were fiction. And, of course, Abe would also live to see the detonation of the first nuclear fission bombs over Japan. No wonder old people in the 20th and 21st century seem stunned by all the changes they’ve witnessed.
But the supreme achievement of Maxwell was to draw all electromagnetic theory together, to formalize it, to compress it, into just four equations. In this half-page of symbols, Abe said... was condensed the whole of Maxwell’s theory... Maxwell’s equations revealed, for Hertz, the lineaments of “a new physics . . . like an enchanted fairyland” -- not only the possibility of generating radio waves, but a sense that the whole universe was crisscrossed by electromagnetic fields of every sort, reaching to the ends of the universe.
p169 With Maxwell we're getting closer and closer to what I'm interested in. This is a great education in science -- though there still needs to be more explanation for some of these ideas. I'm beginning to think I may have to blog this and find links to additional information. Surprise. I'm still not sure I care enough to go to that trouble about less profound aspects here. We've just gotten to fields. That and the physics behind the chemistry is what interests me.
It is astonishing to realize how little people really understood before the late decades of the 19th century. Was understanding the mind of God worth the bad end of the bargain with Mephisto?
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