"the magisterium, our great work, the stone"
"The Alchemist" Act 1. Scene 4
4. - The Philosopher's Stone
Today we remember Sir Isaac Newton (1642-1727) for his contributions to optics, mechanics and astronomy, but as a typical scholar of his time he was also interested in more obscure knowledge, like provided by alchemy. Dedicating himself to this predecessor of chemistry Newton became also involved in early geological research.
The theologian and naturalist Thomas Burnet submitted an early draft of his "Telluris theoria sacra" to Newton in 1680-1681 and Newton exchanged with Burnet some thoughts on the formation of rocks, mountains and even the entire earth. Based on his observations of crystallization of molten tin and saltpeter from water, but also from mixing milk and beer, Newton imagined earth's formation by the crystallization of matter from a primordial and undifferentiated chaos.
Newton never published in full his geological ideas - but some surviving notes deal with (early) geochemical concepts. In two notes dated to 1670, with the title "Of Natures Obvious Laws & Processes in Vegetation" and "Humores mineralis", he supports the "sal nitrum" theory. The crystallization of saltpeter (potassium nitrate - KNO3) is easily observable both in nature as in the laboratory and it was considered by many naturalists of Newton's time as ideal model to understand the growth of minerals, ore veins and rocks in mountains.
In alchemy saltpeter plays a very important role, it was even considered as a sort of philosopher's stone, able to transform into other minerals.
This supposed transformation could explain why minerals were abundant on earth, despite the perpetual dissolution by groundwater percolating into the underground.
Newton notes in "Humores mineralis":
"with the metals continually drawn downwards, never ascending so long as they remain metals, it would be necessary that in a few years the greatest part would have vanished from the upper earth, unless they are conceded to be generated there de novo."
The term "vegetation" in the title of Newton's other note refers to the idea of a spontaneous force generating new metals in the earth's centre and injecting them into earth's crust - alchemy considered principles influencing the inorganic nature very similar (or even identical) to principles acting in life forms. It's therefore no wonder that Newton describes fluids and vapours ("spirits") mating in earth's crust to give birth to the progenitors of metals:
"Indeed, these spirits meet with metallic solutions and will mix with them. And when they are in a state of motion and vegetation, they will putrefy [and] destroy the metallic form and convert [it] into spirits similar to themselves. Which can then ascend again and thus a perpetual circulation of metals takes place."
These progenitors derived from saltpeter, especially sulphur and mercury as two other very important elements in alchemy, will continue to migrate to earth's surface, where the elements will continue to react and transform, finally forming many useful and precious metals. Such metaphysical explanations for the origin of minerals and rocks will prevail for a long time in history.
NEWMAN W.R. (2009): Geochemical concepts in Isaac Newton's early alchemy. In Rosenberg, G.D., ed., The Revolution in Geology from the Renaissance to the Enlightenment. Geological Society of America Memoir 203: 41-49
NORRIS, J.A. (2009): The providence of mineral generation in the sermons of Johann Mathesius (1504-1565). From: K ÖLBL-EBERT, M. (ed.) Geology and Religion: A History of Harmony and Hostility. The Geological Society, London, Special Publications 310: 37-40