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Phosphorus, a highly reactive chemical element found in inorganic rocks, is essential to DNA and RNA and is now used for a variety of purposes, from toothpaste to explosives. Its earlier history provides a good example of where alchemy and science overlap. First discovered in the 1660’s, the Royal Society’s early correspondence and experiments regarding it betray a mixture of spiritual and practical interest, as well as some confusion over what should properly be classed as phosphorus. A from Henry Oldenburg to Marcello Malpighi in 1677 describes the German chemist Balduin sending specimens of phosphorus to both the King Charles II and the Royal Society. Oldenburg notes that this stone (shown by later historians to have been calcium nitrate) ‘absorbs the light of the sun or a lamp that afterwards, in the dark, it radiates like incandescent iron or charcoal’. He also observes that this was a different substance from ‘Bologna stone’, a source of baryte, some species of which, like phosphorus, emit a glow on contact with oxygen. This property of the stone made it the focus of attention from alchemists, who identified it as the long sought after ‘philosopher’s stone’, capable of transforming metals into gold.

The interest of fellows such as Isaac Newton in alchemy is well known and references to alchemic myths such as the Table of Hermes litter the early records. The Royal Society also had more a practical aim in mind, however, in making trials on specimens of phosphorescent materials that they acquired: that of providing an alternative light source to candles and oil-lamps. They were encouraged in this effort by the reports of ‘perpetual noctiluca’ coming out of German at the time. Oldenburg’s letters to Adolf Balduin, who was made a fellow of the Royal Society on the strength of his phosphorus experiments urge him to divulge details of these claims. In February 1682, Hooke reported to the Society that these attempts were still in progress, noting that a Dr Eshalts ‘hoped he should suddainly haue the perpetuall noctiluca as to Enlighten a whole Room being able already to Read a large print by it’. Further correspondence with Eshalts during 1682 discusses the possibility that phosphorus might by made from serum, cows’ milk or human spittle as well as urine.

The Society performed their own experiments with the various phosphorescent materials they were able to obtain. Hooke tried in 1679 to make a type of phosphorus shine after being exposed to the moonlight but failed, even when using a burning glass. On 10 June 1691, the Society witnessed an experiment involving a ‘lapis smargadine’, literally an emerald-coloured stone. This was ground to a powder and placed on a copper plate which was heated, and ‘after the said Powder had been Showed vpon the plate in the shape of R.S. then the Room being Darkened by cloing the Shutters the powder on the plate began to appear white & shining, but [the] All the other parts of the plate did not at all shine for it was not soe great a heat as to make that red hot’. As part of his studies of respiration, Robert Boyle also made experiments with phosphorous wood in an ‘exhausted receiver’, showing that it required a chemical reaction with the air to keep burning (see Fulton’s 1960 article in Notes and Records).
The Philosophical Transactions of 1735 contains some similar experiments using phosphorus synthesized using the ‘acid salt’ (calcium phosphate) of urine as well as an attempt to use it in glass-making. Phosphorescent materials retained their magical allure for some time, and their association with other doctrines of alchemy. For example, a letter to Hans Sloane from a French correspondent dated 1737, stated that phosphorus was a good antidote to the poison of snakes. This idea is one that is constantly associated with bezoar stones, another concept central to alchemy.

Perhaps it is unsurprising that the generation of light, with its innately religious implications, continued to inspire mystical explanations. Likewise, the invention of electricity inspired new religious conceptions, even among those who worked most closely with it, as demonstrated by Noakes’ discussion of Varley’s spiritualism in January’s issue of Notes and Records.

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