Yeoman's Tale") depicts the alchemist as a mere cunning knave. A priest is prevailed on to give the alchemist money, and is told that he will be shown the change of base metal into gold. The alchemist busies himself with preparations, and sends the priest to fetch coals.
"And whil he besy was, this feendly wrecche,
This false chanoun (the foule feende him fecche)
Out of his bosom took a bechen cole
In which ful subtilly was maad an hole,
And therein put was of silver lymayle
An unce, and stopped was withoute fayle
The hole with wex, to keep the lymayle in.
And understondith, that this false gyn
Was not maad there, but it was maad before."
This "false gyn" having been put in the crucible and burned with the rest of the ingredients, duly let out its "silver lymayle" (filings), which appeared in the shape of a small button of silver, and so accomplished the "false chanoun's" end of deceiving his victim.
The alchemists accumulated many facts: they gained not a little knowledge concerning the appearances of Nature, but they were dominated by a single idea. Living in the midst of an extremely complex order of things, surrounded by a strange and apparently capricious succession of phenomena, they were convinced that the human intelligence, directed and aided by the teachings of the Church, would guide them through the labyrinth. And so they entered on the study of Nature with preconceived notions and foregone conclusions: enthusiastic and determined to know although many of them were, they nevertheless failed because they refused to tread the only path which leads to true advances in natural science—the path of unprejudiced accurate experiment, and of careful reasoning on experimentally determined facts.
And even when they had become convinced that their aims were visionary, they could not break free from the vicious system which bound them.
" … I am broken and trained
To my old habits: they are part of me.
I know, and none so well, my darling ends
Are proved impossible: no less, no less,
Even now what humours me, fond fool, as when
Their faint ghosts sit with me and flatter me,
And send me back content to my dull round."[3]
One of the most commonly occurring and most noticeable changes in the properties of matter is that which proceeds when a piece of wood, or a candle, or a quantity of oil burns. The solid wood, or candle, or the liquid oil slowly disappears, and this disappearance is attended with the visible formation of flame. Even the heavy fixed metals, tin or lead, may be caused to burn; light is produced, a part of the metal seems to disappear, and a white (or reddish) solid, very different from the original metal, remains. The process of burning presents all those peculiarities which are fitted to strike an observer of the changes of Nature; that is, which are fitted to strike a chemist—for chemistry has always been recognized as having for its object to explain the changes which matter undergoes. The chemists of the seventeenth and eighteenth centuries were chiefly occupied in trying to explain this process of burning or combustion.
Van Helmont (1577–1644), who was a physician and chemist of Brussels, clearly distinguished between common air and other "airs" or gases produced in different ways. Robert Hooke (1635–1703), one of the original Fellows of the Royal Society, in the "Micographia, or Philosophical Description of Minute Bodies," published in 1665, concluded from the results of numerous experiments that there exists in common air a peculiar kind of gas, similar to, or perhaps identical with the gas or air which is got by heating saltpetre; and he further supposed that when a solid burns, it is dissolved by (or we should now say, it is converted into a gas by combining with) this peculiar constituent of the air.
John Mayow (1645–1679), a physician of Oxford, experimented on the basis of facts established by Hooke. He showed that when a substance, e.g. a candle, burns in air, the volume of air is thereby lessened. To that portion of the air which had dissolved the burned substance he gave the name of nitre-air, and he argued that this air exists in condensed form in nitre, because sulphur burns when heated with nitre in absence of common air. Mayow added the most important fact—a fact which was forgotten by many later experimenters—that the solid substance obtained by burning a metal in air weighs more than the metal itself did before burning. He explained this increase in weight by saying that the burning metal absorbs particles of "nitre-air" from the atmosphere. Thus Hooke and Mayow had really established the fact that common air consists of more than one definite kind of matter—in other words, that common air is not an element; but until recent times the term "element" or "elementary principle" was used without any definite meaning. When we say that the ancients and the alchemists recognized four elements—earth, air, fire, and water—we do not attach to the word "element" the same definite meaning as when we now say, "Iron is an element."
From earth, air, fire and water other substances were obtained; or it might be possible to resolve other substances into one or more of these four. But even to such a word as "substance" or "matter" no very definite meaning could be attached. Although, therefore, the facts set forth by Hooke and Mayow might now justify the assertion that air is not an element, they did not, in the year 1670, necessarily convey this meaning to men's minds. The distinction between element and compound was much more clearly laid down by the Hon. Robert Boyle (1627–1691), whose chemical work was wonderfully accurate and thorough, and whose writings are characterized by acute scientific reasoning. We shall again return to these terms "element" and "compound."
But the visible and striking phenomenon in most processes of burning is the production of light and sometimes of flame. The importance of the fact that the burned substance (when a solid) weighs more than the unburned substance was overshadowed by the apparent importance of the outward part of the process, which could scarcely be passed over by any observer. There appears to be an outrush of something from the burning substance. There is an outrush of something, said Becher and Stahl, and this something is the "principle of fire." The principle of fire, they said, is of a very subtle nature; its particles, which are always in very rapid motion, can penetrate any substance, however dense. When metals burn—the argument continued—they lose this principle of fire; when the burned metal—or calx as it was usually called—is heated with charcoal it regains this "principle," and so the metal is re-formed from the calx.
Thus arose the famous theory of phlogiston (from Greek, = "burned"), which served as a central nucleus round which all chemical facts were grouped for nearly a hundred years.
John Joachim Becher was born at Speyer in 1635, and died in 1682; in his chemical works, the most important of which is the "Physica Subterranea," he retained the alchemical notion that the metals are composed of three "principles"—the nitrifiable, the combustible, and the mercurial—and taught that during calcination the combustible and mercurial principles are expelled, while the nitrifiable remains in the calx.
George Ernest Stahl—born at Anspach in 1660, and died at Berlin in 1734—had regard chiefly to the principles which escape during the calcination of metals, and simplifying, and at the same rendering more definite the idea of Becher, he conceived and enunciated the theory of phlogiston.
But if something (name it "phlogiston" or call it by any other name you please) is lost by a metal when the metal is burned, how is it that the loss of this thing is attended with an increase in the weight of the
