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Uncle Tungsten
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Chemistry as a true science, I read, made its first emergence with the work of Robert Boyle in the middle of the seventeenth century. Twenty years Newton's senior, Boyle was born at a time when the practice of alchemy still held sway, and he still maintained a variety of alchemical beliefs and practices, side by side with his scientific ones. He believed that gold could be created, and that he had succeeded in creating it (Newton, also an alchemist, advised him to keep silent about this)...
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All these... [his investigations into crystals, color, electricity, chemistry] he described in language of great plainness and clarity, utterly different from the arcane and enigmatic language of the alchemists. Anyone could read him and repeat his experiments; he stood for the openness of science, as opposed to the closed, hermetic secrecy of alchemy.
p103 ...He wished, above all, to understand the nature of matter, and his most famous book, The Sceptical Chymist, was written to debunk the mystical doctrine of the Four Elements, and to unite the enormous, centuries-old empirical knowledge of alchemy and pharmacy with the new, enlightened rationality of his age.
The ancients had thought in terms of four basic principles or elements -- Earth, Air, Fire, and Water. I think these were pretty much my own categories as a five-year-old child (though metals may have made a special, fifth category for me), but I found it less easy to imagine the Three Principles of the alchemists, where "Sulfur" and "Mercury" and "Salt" meant not ordinary sulfur and mercury and salt but "philosophical" Sulfur, Mercury, and Salt: Mercury conferring luster and hardness to a substance, Sulfur conferring color and combustibility, Salt conferring solidity and resistance to fire. [According to Wiki the Three Principles are a Muslim concept.]
Boyle hoped to replace these ancient, mystical notions of Elements and Principles with a rational and empirical one, and provided the first modern definition of an element:
I now mean by Elements {he wrote} . . . certain Primitive and Simple, or perfectly unmingled bodies; which not being made up of any other bodies, or of one another, are the ingredients of which all those call'd perfectly mixed Bodies are immediately compounded, and into which they are ultimately resolved.
But since he gave no examples of such "Elements" or of how their "unmingledness" was to be demonstrated, his definition seemed too abstract to be useful.
To jump way ahead, if Boyle is the start of this process, the culmination would be Murray Gell-mann and QCD.
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p104 Evacuating air from a closed vessel that contained a lit candle or a glowing coal, Boyle found that these ceased to burn as the air was rarefied... thus showing that air was necessary for combustion... [The same was true with insects, birds and mice were similarly extinguished by a lack of air] He was struck by the similarity between combustion and respiration.
(Note: Hooke...[Boyle's assistant] showed an intellectual audacity sometimes even greater than Boyle's, as with his understanding of combustion, which, he said, "is made by a substance inherent, and mixt with the Air." He identified this with "that property in the Air which it loses in the Lungs." This notion of a substance present in limited amounts in the air that is required for and gets used up in combustion and respiration is far closer to the concept of a chemically active gas than Boyle's theory of igneous particles... [Hookes insights were ignored at the time because they were,] so radical as to be unassimilatable, even unintelligible, in the accepted thinking of his time.)
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p105 Boyle's personality appealed to me greatly, as did his omnivorous curiosity, his fondness for anecdote, and his occasional puns (as when he wrote that he preferred to work on things "luciferous rather than lucriferous"). I could imagine him as a person, and a person I would like, despite the gulf of three centuries between us.
p106 Antoine Lavoisier, born almost a century after Boyle, would become known as the real founder, the father, of modern chemistry...
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[Prior to Lavoisier] There was... no overall theoretical framework in which chemical phenomena could be placed, only the somewhat mystical theory of phlogiston... Phlogiston was the principle of Fire. Metals were combustible, it was supposed, because they contained some phlogiston, and when they burned, the phlogiston was released. When their earths were smelted with charcoal, conversely, the charcoal donated its plogiston and reconstituted the metal. Thus a metal was a sort of composite or “compound” of its earth, its calx, and phlogiston. Every chemical process -- not only of smelting and calcination, but the actions of acids and alkalis, and the formation of salts -- could be attributed to the addition or removal of phlogiston.
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p107 It was into this half-metaphysical, half-poetic atmosphere that Lavoisier -- hardheaded, keenly analytical and logical, a child of the Enlightenment and an admirer of the Encyclopedists -- came of age in the 1770s. [Contemporary with Goethe.] ...
p108 In 1772 Lavoisier read of the experiments of Guyton de Morveau, who had confirmed in experiments of exceptional precision and care that metals increased in weight when they were roasted in air...
p109 ... Lavoisier set to systematic experiments, repeating many of his predecessors’ work, but this time using a closed apparatus and meticulously weighing everything before and after the reaction, a procedure which Boyle, and even the most meticulous chemists of Lavoisier’s own time, had neglected. Heating lead and tin in closed retorts until they were converted to ash, he was able to show that the total weight of his reactants neither increased nor decreased during a reaction. Only when he broke open his retorts, allowing air to rush in, did the weight of the ash increase -- and by exactly the same amount as the metals themselves had increased in being calcined. This increase, Lavoisier felt, must be due to the “fixation” of air, or some part in it.
In the summer of 1774, Joseph Priestly... found that when he heated red calx of mercury (mercuric oxide) it gave off an “air” [oxygen] which, to his amazement, seemed even stronger or purer than common air.
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p110 ...[Lavoisier] repeated Priestley’s experiments, amplified, quantified, refined them. Combustion, it was now clear to him, was a process involving not the loss of a substance (phlogiston), but the combination of the combustible material with a part of atmospheric air, a gas, for which he now coined the term oxygen. [By 1783 there were improved lamps on the market which took advantage of this insight into oxidation and combustion.]
p111 Lavoisier’s demonstration that combustion was a chemical process -- oxidation, as it could now be called -- implied much else, and for him was only a fragment of a much wider vision, the revolution in chemistry that he had envisioned... [the constancy of weight before and after reactions suggested a “principle of conservation”] This principle of conservation, moreover, applied not only to the total mass of products and reactants, but to each of the individual elements involved. When one fermented sugar with yeast and water in a closed vessel to yield alcohol... the total amounts of carbon and hydrogen and oxygen always stayed the same. They might be reaggregated chemically, but their amounts were unchanged.
...Thus Lavoisier was led to define an element as a material that could not be decomposed by existing means, and this enabled him (with de Morveau and others) to draw up a list of genuine elements --thirty-three distinct, undecomposable, elementary substances, replacing the four Elements of the ancients. This is turn allowed Lavoisier to draw up a “balance sheet,” as he called it, a precise accounting of each element in a reaction. [How bourgeois.]
p112 The language of chemistry, Lavoisier now felt, had to be transformed to go with his new theory, and he undertook a revolution of nomenclature, too... If an element was compounded with nitrogen, phosphorus, or sulfur, it became a nitride, a phosphide, a sulfide. If acids were formed, through the addition of oxygen, one might speak of nitric acid, phosphoric acid, sulfuric acid; and of the salts of these as nitrates, phosphates, and sulfates. If smaller amounts of oxygen were present, one might speak of nitrites or phosphites instead of nitrates and phosphates, and so on. Every substance, elementary or compound, would have its true name, denoting its composition and chemical character, and such names, manipulated as in an algebra, would instantly indicate how they might interact or behave in different circumstances...
Lavoisier did not provide symbols for the elements, nor did he use chemical equations, but he provided the essential background to these, and I was thrilled by his notion of a balance sheet, this algebra of reality, for chemical reactions. It was like seeing language, or music, written down for the first time. Given this algebraic language, one might not need an actual afternoon in the lab -- one could in effect do chemistry on a blackboard, or in one’s head.
p113 ...The path to his revolution was not easy or direct, even though he presents it as obvious in the Elements of Chemistry; it required fifteen years of genius time, fighting his way through labyrinths of presupposition, fighting his own blindnesses as he fought everyone else’s.
...when the Elements was finally published -- in 1789, just three months before the French Revolution -- it took the scientific world by storm. It was an architecture of thought of an entirely new sort, comparable only to Newton’s Principia... by 1791 Lavoisier could say, “all young chemists adopt the theory and from that I conclude that the revolution in chemistry has come to pass.”
Three years later Lavoisier’s life was ended, at the height of his powers, on the guillotine...
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