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To the Right Honourable the Lords Commissioners of his Majestys Treasury the Memorial of Sir Isaac Newton most humbly sheweth

Cours copper when made read hot will not spread under the hammer but flyes in pieces. And in refining it, so soon as it begins to spread under the hammer when made red hot, it begins to be called fine copper, & then it is worth about 13d per poundweight, & when it is fine enough to beare the great hammers of the battering mills, it is reputed fine copper free from all mixtures & is then valued at about 14d12 per poundweight. And of about this degree of fineness was the copper money coined in the reign of King Charles II, it being of Swedish copper manufactured into blanks in Sweden. And of about the same degree of fineness is all such copper as being made red hot will then spread very thin under the hand hammer upon an anvill without cracking And by his Majesties Warrant the money ought to be of this degree of fineness Copper may be refined to a much higher degree so as to be worth 2s or 2s 6d per poundweight or above. But such copper is of little use except for making wire or leafe copper/ & there is no certain assay or rule yet known by which the fineness of it may be ascertained & the highest degre to which it may be refined is not yet known There have been blanks made of much fined copper then the money by people not imployed by me & stamped in the Mint without my knowledge & then polished to give them a more beautifull gloss & shewn about to deceive people & bring the money into discredit, & brockage hath also been picked out of the money & shewn about a parcel of money received from the Mint, & there may have been blanks of coarse copper carried to the Mint & there stamped without my knowledge, or otherwise counterfeited, & mixed with the brockage. The goodnes of copper cannot be known by the looks alone. It must be assayed. By the colour & grain of the copper when it is newly broken some judgment may be made by a skilful person: but the surest trial is by the malleability of the copper hot & cold. And therefore this was made the assay of standard copper by his Majestys Warrant, & by this assay the Pix of what has been coined is to be tried.

© 2024 The Newton Project

Professor Rob Iliffe
Director, AHRC Newton Papers Project

Scott Mandelbrote,
Fellow & Perne librarian, Peterhouse, Cambridge

Faculty of History, George Street, Oxford, OX1 2RL - newtonproject@history.ox.ac.uk

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