Newton and alchemy: the papers and the laboratory

Yes: Isaac Newton was an alchemist. For decades Newton read, copied, annotated and practised alchemy, and of the 329 lots of Newton manuscripts that Sotheby's auctioned in 1936, over a third had content that was “undeniably alchemical”, according to the Indiana University project that edits them.¹ What is not known for certain is what it was for. The previous article told how Paracelsus turned alchemy into a chemistry of medicines; a century later, the man of gravitation still had one foot in it. Here is what Newton's assistant told, what was copied, what was published in the Opticks and how later ages judged it.

Was Newton an alchemist?

When Newton died in 1727, those papers were labelled “not fit to be printed”, and they stayed in the family until the 1936 auction, which was, the Indiana editors write, “a rude shock” to Newton scholarship.¹ According to Wikipedia, many were bought by the economist John Maynard Keynes, who on the strength of them described Newton as “the last of the magicians”.² Nor were they stray papers: the editors stress that Newton's laboratory notebooks, including the one containing the first full description of the discovery that white light is a mixture of colours, “are filled with recipes patently elaborated from the very alchemical sources”, alongside “Neptune's Trident”, “Mercury's Caducean Rod” and the “Green Lyon”. Their conclusion: we “cannot erect a watertight dam” between Newton's alchemy and the rest of Newton's science.¹

What the assistant saw

The most direct testimony is that of Humphrey Newton, secretary to Newton in Cambridge from 1684 to 1689. In two letters from early 1728, published by David Brewster in 1855, Humphrey told what was seen: in spring and in autumn Newton spent about six weeks in the laboratory, “the fire scarcely going out either night or day”, the two of them taking turns to sit up with it. “What his aim might be I was not able to penetrate into, but his pains, his diligence at these set times made me think he aimed at something beyond the reach of human art and industry.”³

The second letter is more specific. The laboratory was well furnished with bodies, receivers and crucibles, though little used except the crucibles, “in which he fused his metals”; sometimes Newton would look into an old mouldy book kept there, “I think it was titled Agricola de Metallis”, and Humphrey writes: “the transmuting of metals being his chief design, for which purpose antimony was a great ingredient”.³ It is what an assistant understood, not what Newton said; but it is as close as one can get to that laboratory.

What Newton read and copied

Brewster saw the alchemical papers before the auction and left a list: in Newton's hand, The Metamorphoses of the Planets by Johann de Monte Snyders, in 62 pages, with a key; many pages of alchemical poetry from Norton's Ordinal and from Basil Valentine; a copy of Secrets Revealed (1669), by the author who signed as Eirenaeus Philalethes, “covered with notes” by Newton; and a very large Index Chemicus, an index of alchemical subjects with minute references.³ That index is now transcribed, in alphabetical order and in Latin, and reads like a dictionary of alchemy: Aquila, the eagle; Avis Hermetis, the bird of Hermes; Caduceus; Aurum potabile, drinkable gold; Bufo, the toad.¹

Newton's symbols

Newton wrote alchemy in symbols, and not always the usual ones. According to the Indiana guide, Newton's use of alchemical symbols was “creative and unorthodox”: the planetary symbols for the metals, like everyone, but also “a multitude of additional, more personal pictograms”. The easiest to decipher are those for ores: the metal's symbol with an “o” attached, for “ore”. In other cases, a horizontal line through a circle may indicate a salt; a cross atop a circle, an antimonial compound; and the sal ammoniac star attached to a symbol, that the substance is volatile. And the editors admit that “at present the editors do not claim to have exact knowledge” of what most of these compound symbols refer to.⁴

Alchemy inside the science

In what Newton published there is little alchemy on view, but not none. In Query 30 of the Opticks, in the 1730 edition: “The changing of Bodies into Light, and Light into Bodies, is very conformable to the Course of Nature, which seems delighted with Transmutations.” And the example given is mercury, which appears sometimes as a fluid metal, sometimes as a corrosive salt called sublimate, sometimes as a red earth “call'd Cinnaber”, “And after all these Changes it returns again into its first form of Mercury.”⁵ It is the chemistry of its time, but the vocabulary, Nature's transmutations, is alchemy's. The Indiana editors use the 17th-century word “chymistry” so as not to separate what then went together: technology, medicine and the search for gold.¹

How later ages judged it

In 1855 Brewster, an admirer of Newton, could not stomach this. Brewster argued that the alchemy of Boyle, Newton and Locke was prompted by “the ambition neither of wealth nor of praise” but by “a love of truth”, and still wrote: “we cannot understand how a mind of such power, and so nobly occupied with the abstractions of geometry, and the study of the material world, could stoop to be even the copyist of the most contemptible alchemical poetry, and the annotator of a work, the obvious production of a fool and a knave.”³ From what is said a few pages earlier, the annotated work was Philalethes's.

Almost a century later, with the papers auctioned, Keynes turned the verdict around and called Newton “the last of the magicians”.² Both sentences say more about their age than about Newton. Today's editors prefer not to choose: to study what Newton did, with which texts and with what results.

Did mercury poison Newton?

In 1693 Newton suffered a nervous breakdown and wrote accusing letters to friends such as Samuel Pepys and John Locke. According to Wikipedia, mercury was later found in Newton's hair, probably from the experiments, and poisoning could explain some of Newton's eccentricities.² It is not settled: in 1983 The Lancet published an article titled “Isaac Newton: mercury poisoning or manic depression?”.⁶ I did not read those studies, and have no way to decide between them. What can be said is what the assistant told: that Newton melted metals in crucibles for weeks, with the fire burning day and night.

What I could not read

I did not read Newton's alchemical manuscripts, which the Indiana project edits and transcribes; from its website I read the introduction, the symbol guide and the list of the Index Chemicus. Of Brewster, chapter XXV and Humphrey Newton's letters in the second volume; of the Opticks, Query 30. Keynes, Newton's hair and the 1693 crisis come from Wikipedia; of the Lancet article I know only the title. Nor did I read Philalethes or Snyders.

What we do with this

What Newton teaches us most here is the assistant: someone who watched closely for five years, told what was seen and said plainly what was not understood. At the Observatory we try the same: show what can be seen and not pretend to know what we do not.