Holograph draft memorandum on methods of assaying gold and silver by refinement, such as should be used in assessing trial pieces Isaac Newton c. 509 words The Newton Project Oxford 2017 Newton Project, University of Oxford

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 Probably after 21 August 1710, c. 509 words.

These were not used in assessing the 1707 trial piece. Objects further that trial pieces should be made only by royal order, whereas the 1707 one was made merely on the authority of the Treasurer's warrant.

 MINT 19/1/293, National Archives, Kew, Richmond, Surrey, UK UKSurreyKew, RichmondNational Archives MINT 19/1/293 Probably after 21 August 1710 England English Holograph MintPyx Trials and Analyses of British Coinage Catalogue information compiled by Rob Iliffe, Peter Spargo & John Young Catalogue exported to teiHeader by Michael Hawkins Transcribed by Will Scott
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Gold & Silver are assayed by refining them & observing how much they are lightned by refining.

Silver about b is assayed & refined by melting it wthwith thrice its weight of lead & keeping it in fusion till the lead fumes away & carries with the base metals.. & The silver wchwhich remains is fine silver. Itf it be refined again with thrice its weight of Lead it becomes finer then before, butthe lead carriying away a little more of the base metals. But silver once refined is fine silver or silver 12 ounces fine by the laws of all Europe. And eleven ounces two penny weig weight of this silver melted in a mass& well mixed wthwith18dwt of copper makes standard silver by the law of England. And of such a mixture yethe standard trial pieces of silver ought to be made.

Gold is assayed & refined by melting it wthwith thrice its weight adding it to it twice its weight of silver & melting the mixture with thrice its weight of led till the lead fumes away & carries away with it all the base metal & leaves the gold & silver alone, wchwhich being hammered into a thin plate & put into a gla hot aqua fortis, the aqua fortis eats away the silver & leaves the gold alone. If this aqua fortis be poured off & fresh aqua forteis be poured on, this second water (especially if it be a little stronger then the former) & will eat away a little more of the silver & leave the Gold finer then before. And a third water will leave it still finer, & a fourth still finer. And But Assaymasters & Refiners proceed no further then to two waters. Gold assayed or refined with two waters is fine Gold ior Gold 24 carats fine by the laws of all Europe, & Eleven ounces of such fine Gold melted into a mass& well mixed with one ounce of allay in f make standard Gold by the law of England: And of such a mixture the standard triall pieces of Gold ought to be made.

The standard pieces should be made by the Queens Order, as yethe Indenture of the Mint expresses, but were made the last time (A. C. 1707) by the Lord Treasurers warrant. The Iury did not then refine the Gold & Silver but bought them ofoff my Deputy Mr Carlich. & They know not how he refined them, butand wondred that he could make them so fine.: The trial pieces Iury But being generally of opinion that no gold or silver could be too fine, they made the trial pieces thereof for the money but absolutely refused to give receipts for of of theirm trial pieces for making their plate thereby. And these Trial pieces were never yet established under the broad seal, but being as they ought to be. And if they be established the Merchants will thereby lose about 4 or 5s in the pound wtweight of all gold imported.