Report on a new design of furnace in Cornwall for melting tin

Author: Isaac Newton

Source: MINT 19/3/546-7, National Archives, Kew, Richmond, Surrey, UK

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- Revision History
  - 1 January 2001
    - Catalogue information compiled by Rob Iliffe, Peter Spargo & John Young
  - 29 September 2011
    - Catalogue exported to teiHeader by Michael Hawkins
  - 7 September 2016
    - Transcribed by Will Scott
  - 25 September 2016
    - Will Scott finished transcription
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<546r>

To the R^t Hon^ble the Earl of Godolphin Lord High Treasurer of great Britain

May it please yo^r Lord^p

Since our late Report \presented to yo^r Lord^p/ concerning the melting of Tin-Oar in Reverbarating Furnaces in Cornwal by the Patentees, |t|her Majesties\Deputy/ Assaymaster \of Tin/ hath cutt off Assay pieces from several Blocks of Tin in Cornwal some of w^ch Blocks were melted in the Furnaces & others in the Blowing houses, & has assayed the pieces in the Tower & found both sorts much of the same goodness. The Agent of the Patentees sent us other Assay pieces cut off from Blocks melted in the Furn{illeg}|a|ces w^ch were assayed also in the Tower by |t|her|\Deputy/| Ma^ties AssayMaster & found of the same goodness with the former. All these Assays being taken from west country Tin, where very little grain Tin is produced, none of them proved to be grain Tin: but the Patentees affirm that since they began to melt the several sorts of Tin apart, that is, in the three last coynages not yet sent to the Tower, a good quantity of their Tin breaks grain.

Some Gentlemen affirm that above one tenth part of all the Tin in Cornwal used heretofor to prove grain Tin, & think that the Furnaces of the Patentees by keeping the Tin too long in fusion evaporates the best parts of it & spoiles the grain Tin. {sic} |& damages the rest.| And if this proves true we are humbly of opinion that the Patent is injurious to the Tin affair. But others represent that not above one twentieth part of all the Tin in Cornwall used heretofore to prove grain Tin, & that the Tin is refined from the drossy parts by being kept in fusion & thereby becomes better then before. And the Patentees tell us that their Agent in Cornwall hath by their Order kept a parcel of Tin in fusion in the heat of their furnaces some hours together & found it finer & better Tin after the fusion then before; whereas in their usual way of melting Tin out of the Oar, it continues in fusion but about a quarter of an hour.

We having no Tin Oar nor Blowing houses & Melting houses to decide this important Question, do therefore humbly propose that yo^r Lord^p would please to give Order to the Agents in Cornwal, that this matter be there examined by taking out of the same heap of the black Oar of grain Tin, after it has been washed in the usual manner & made fit to be melted & is well mixed together, two equal parcels, & causing the one to be melted in a Blowing house, the other in a Furnace of the Patentees, & run into Blocks fit for coynage in the usual manner, and that |t|her Majties Deputy Assaymaster & such other sufficient Witnesses as the Agents in Cornwall shall think fit to appoin appoint do see that the whole proceeding in both the melting <546v> house & the blowing house be done in the usual manne|r,| & that the Blocks produced be assayed in their presence by |t|her Maj^ties {illeg}|de|puty Assaymaster, & the experiment of melting & assaying be repeated once or twice,\oftener/ if need by, for the greater certainty, & the whole matter reported by the said Agents to your Lord^p.

We also humbly propose that a parcel of good grain Tin be kept in fusion, in the presence of the same Witnesses, four or six hours, in the|at| same heat of a furnace w^ch is used in melting the Oar, & that |that {sic} at the end of every two hours the molten{the} Tin be \well/ stirred & {two} to mixt it equally eavenly & tw{illeg}|o|| assays be taken out of the furnace every two hours\one immediately before the stirring & another soon after it presently after it/ & y^t these assays be compared by |t|her Maj^ties Deputy Assaymaster \with one another &/ with an assay-piece cut off from the Tin before fusion, to see whether \& how much/ the Tin grows better or worse by the fusion \& stirring/: & a \distinct/ Report thereof |\together/ w^th an account of the dross found in the bottom of the furnace by keeping the Tin in| |fusion some time after the last assay is taken out| be sent by the Agents to your Lordship. And that the/We also desire that the\ Agents /will please to\ inform themselves also, as well as they can, of the quantity of grain Tin which used heretofore to be made annually in Cornwall in proportion to the other sorts of Tin, & of the quantity, or number of blocks, of grain Tin made th{is}|e| {Lady|last|} \last/ coynage by the Patentees, & give your Lordship an account thereof.

All which is most humbly submitted to yo^r Lord^ps great Wisdome

^[1] <547r>

^[1] Mint Office,
April 1708.