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[Section. 1] AS all Coppers come black out of the Oars upon melting, yet some much fi∣ner and cleaner than others, which must after be cleansed and made ready, as they which contain no silver, and not purified, must be made ready and deft: Also to know certainly how many Centners of it after
cleansing it yields of clean Copper (which must be pro∣ved in a little Fire.) Some think it may be known by * 1.1special copper Touch-Needles, made on purpose: but be∣cause the black-Coppers are not all alike, but some iron∣streamy, some tinny, spizy or leady, I cannot certainly determine concerning such Proofs: But the best way is thus, First, cut off from the cast Copper Ingot, and weigh 2 or 3 Centners of it, and lute a Test with small ground leady Glass, put the weigh'd Copper in it, and blow it in a fresh coal fire, till it hath a clean green copper Colour, then presently, take the Test out of the Fire, and take the Copper out of the slacks, and quench it off, then cut it asunder with a Chissel, and you will see whether it be good: then weigh and count how much the inset black Copper hath yielded ready Copper.
[Section. 2] * 1.2This proof, although the Copper be surer to be found, than by the Touch-Needles, yet 'tis not certain to ground upon; because the Proof is small and the Cop∣per little, therefore very easily the Fire may take away somewhat too much if it be over-burnt, which in great Works cannot be done, and so somewhat more of red copper will be brought out.
If you will have the right proof, and know the right Content, the same must not be esteemed too great a La∣bour, to make more than one Proof of the black-Copper, and then take the middle out of it.
You may use to this Proof, Borax, which cleanseth the Metal much, and brings the copper to be sooner ready: but, because one cannot use Borax in the great Works, it were better this proof (especially iron-streamy Copper) might be helpt with a little clean Lead, because 'tis used in cleansing: and the copper will become leady, which doth much cleanse the Copper, but if the copper [Section. 3] * 1.3be leady, then there needs no lead to be added.
Some Assayers use this Method in their Proofs, viz.
They take a Test which is made moist, and make a lit∣tle hearth in it of Coal Powder, mixt with clay, having a flat smooth hole cut out: upon this they set the cop∣per which is to be proved, and blow it with the Addi∣tion of a little Lead-glass, this will the sooner make it ready, but I think there is small difference in what ever is driven off from it: but be sure you drive not the copper too hard, and yet let it be of a right copper or blick colour.
[Section. 4] * 1.4And, because many times copper-flints are to be found, in which almost the half is Tinn-stone, and if cop∣per be melted out of it, it would be very tinny and spi∣zy, also if it were done among other coppers, all would be spoiled in the cleansing. To prevent this, there is a particular way, viz. that by beating and washing one may separate both Mettals by bucking or cleansing, and then melt every part asunder, and bring it to profit; of which way I should write something here, but be∣cause I do not give a full Instruction in these my Books of the great Works viz. of Bucking, Washing and Smelting Metal Oars) but only lesser Works, therefore I will here end, till another more convenient time, when they may be further discoursed of.
Of Copper Needles.
This Proof not certain.
Another Manner.
Copper flint and Tin stone may be Seperated.