A collection of notes by the 17th century English mathematician and physicist Sir Isaac Newton, that scientists thought had been lost forever, have been found.
The notes on alchemy were originally discovered after Newton's death in 1727 but were lost after they were sold at auction in July 1936 for 15 pounds ($27).
They were found while researchers were cataloguing manuscripts at the Royal Society, Britain's academy of leading scientists.
"This is a hugely exciting find for Newton scholars and for historians of science in general," Dr John Young, of London's Imperial College Newton Project, said in a statement on Friday.
Newton's celebrated work "Philosophiae Naturalis Principia Mathematica" (or Mathematical Principles of Natural Philosophy) is considered one of the most important works in the history of modern science.
In it he formulates the three laws of motion and that of gravity.
Some scientists in Newton's time believed alchemy held the secret of how to transform base metals into silver or gold. Newton's notes were written in English in his own handwriting.
"It provides vital evidence about the alchemical authors Newton was reading, and the alchemical theories he was investigating in the last decades of the 17th century," Young added.
The notes will be on display at the Royal Society's annual Summer Science Exhibition in London which begins on July 4.