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[Section. 1] IF you have Pieces of Gold either in Plates or Ingotts, and wouldst assay them, then first cut Pieces or Plates a∣bove, at one end of it, and below at the other end, and beat the Bits thin that you may weigh so much as you have necessity to use for a tryal, but if it is a cast Ingot, then
beat it thin only at one end, and weigh of it for thy Tryal.
[Section. 2] To such a Tryal of Gold and Gold-Gilders, you must have a particular Carat-weight fitted for it, and it must be small because of the Silver-cut, otherwise the Ballance cannot carry the Cut (concerning which shall be treated of hereafter) the dividing of the Carat weight is as followeth.
If you would prove the Gold, see if it be of a rich or poor Content, and would also certainly judge how much a Mark▪ of it hath of fine Gold, then you must know first (and before the nearest Content of the Gold according to which you are to make your Tryal, as shall follow.) That for such contents you shall have two sorts of wayes to inform your self, First, by the Touch with the before made Golden Touch-Needles;) Secondly, One may make a nearer Trial of the Gold, for, although the Proof do not remain whole in the A∣qua fort▪ yet you may see very near what the Gold doth
hold, Therefore it is best to use the Assay-proof upon [Section. 3] it, by which one may also find, what the Gold contain∣eth both in white or fine Silver. When now you have found by these waies the nearest content of the Gold, then make the cut of fine Silver (which must be with∣out Gold;) take then the Gold and beat it with a Ham∣mer upon an Anvil fine and thin, and make thy cut so, that the white or Silver, which is already with the Gold) may be counted with the Tryal or fourth part (for it must contain three times as much Silver as of fine Gold.) To comprehend this the better, the following Example shall demonstrate it, which I have found by the tryed Proof, that of the Gold which containeth 14 Carats, 8 grains of fine Gold, and 7 Carats, and four grains of white; I weigh it with the small carat weight to two alike half-Marks, then there will be in every half Mark 7 carats, and four grains of Gold, and 3 Ca∣rats and eight grains of white, to which I add three times the weight of fine Silver as the gold containeth of fine gold; this is my Proportion. Now I do multiply [Section. 4] the seven carats and four grains (which containeth the half Mark) of fine gold, with three, and there will come 22 carats of white or Silver to the Addition or to the Cut: from this I reckon, That of three carats, and eight grains of white there will be as much as the half Mark had of Silver with it before, so there will remain 18 carats, and 4 grains, and thus much fine Silver you must add in an half Mark.
[Section. 5] As this Silver or Cut and the half weighed Mark do make together 30 carats, and 4 grains, so much also must be the inweighed gold, of the other half Mark cut. Put every one of these with its Cut upon a well neal∣ed Copel, and add nine weights of pure Lead into it, let it go off together, and see whither the grains come a∣like, then lay one of the grains in the Scale, and as much
as it now weigheth less than thirty carats and four grains, so much containeth a half Mark of Gold-Red-Copper, but to the fine Silver because it looseth upon the Copel, if it goeth off upon it with Lead as much as the Lead hath carryed away, may by a grain weight be account∣ed; for, understand it thus; In case every grain did weigh after it was gone▪ of 29 carats, and 4 grains: also a grain wast of fine Silver, there would be wasted one Carat upon the half Mark, then there will come upon the whole Mark two carats; thus much Copper (or red) containeth a Mark of mixt Gold.
[Section. 6] If the grains are diligently drawn and weighed, then beat out of every grain a fine and clean piece or Roll, not too thin, and glow it often that it may not be shive∣ry, and that nothing may go off; at the last glow the little Roll, and roll it gently over, that you may see whether by the often glowing and beating somewhat be come off: When now the Rolls are clean prepared, glow them once more, and if they from the glow∣ing and rolling be come hard, let such things be men∣ded.
[Section. 7] But the glowing must be done in a golden little half Pipkin made on purpose, that nothing unclean may come in it, put then the Rolls together in a little separating Glass, put to it near so much Aqua fortis made for Gold∣proofs, that it may go an half finger broad over the lit∣tle Rolls, stop the Separating Glass above with a hard twisted paper, that no vapors may go out, and put it thus into a little Vessel of Iron or brass made on purpose, over a few live Coals, that the Aqua fort. may begin to work, so will the separating-Glass become brown, but let it not work too much or too fast, yet take it a little while from the fire, and then put it on again, un∣till the Aqua fortis hath done its working, and the Glass become white again: Then put off the Aqua fortis
again and put fresh Aqua fortis upon it, set it again with the Vessel over the fire, and let it work: this is done, because if the first Aqua fort. were grown too weak, and had lost somewhat of Silver by the Rolls, that the other Aqua fort. might touch it again, and make it clean. Take notice also, That you may cause the last Aqua fort. to work in great Bubbles, that the Roles may become very clean, and put in the second Aqua fort. which hath not beenused, for it hath its strength as before.
[Section. 8] Then put clean sweet warm water upon the little Rolls, (Rain Water is the best for it) let it stand a little, and put more warm, or rain Water, upon it again, and set the Glasses with the Rolls over a coal fire, let it boil and work in great Bubbles, then take it off, and casting the water again away, this do three times with warm or rain water, that the silvery Aqua fort. which did hang about the little Rolls be dulcified, then is it enough: When the little Rolls are thus clean and sweet, then put them out very gently, with the last sweet water in a glaz'd pot or glass bottle, and pour the water off from it, and take the Golden Rolls with clean Pincers out of the Pot, and put them in a clean cloth to suck the rest of the water into it, and the Rolls will look very fine and brown.
[ 9] Then put them into the Golden pott, and after, put them into an Assay-Oven, but not in an exstream heat∣ing, and glow them well and they will become as fine as a pure Gold: When this is done, Take the two little Rolls, weigh them one against the other, and if they are alike in weight, then have you proved them right: next, put them together in a weigh-scale, and weigh them with the Carat-weight, and how much they do weigh, so much containeth the Mark (of the mixt Gold) in fine Gold: this only is to be observed, That the weight of the Wa∣ter,
(as much as the Water hath left after it with the Golden Rolls) must be substracted always in the Weight from such Content. But how much there will be to substract you must search with a singular Proof, with which you use to prove the Aqua fort. but when you have once proved the Aqua fort. then you have no need to prove it any more, but may keep it for use: yet 'tis commonly found that upon a Mark of fine Gold, as from 24 carats you must substract one and a half, sometimes two grains for the weight of the water, and so you must substract according to the Example of the before mentioned Proof, as upon 14 carats, and 9 grains, as much as the Golden Roll of one grain, did weigh, then there will remain 14 carats and 8 grains of fine gold, for in the gold proof, in many places, one useth not to give in, in buying, a half grain, but in the coin-works they use all wayes to count, and give in the half grain: If then the little Rolls contain in fine gold 14 carats and eight grains, then a mixt mark of Gold will contain 7 carats and four grains of white or fine silver substracted.
Now, the Gold of 24 carats and 8 grains of the whole cut, and 24 carats of Gold & 44 Carats of silver, you shall finde (as I have said) that the Contents will be a mixt▪ mark, 14 carats 8 grains of fine gold, and 7 carats, and 4 grains of white, and two carats of red, and these three Contents will make together a full Mark.
[Section. 10] After this manner and method are to be proved all other Golds, likewise the coyned Gold, and one needeth not the Assay-Proof, in the coined Gold, if one know∣eth the nearest Contents, but if one doth not know the Contents certain upon a carat, then an Assay of it must be made.
[Section. 11] Now I use this Method in my Cut (and common∣ly on the silver or Cut) to take two carats or some∣what
less for a tryal which doth agree with the Multi∣plication (as above-heard, of the three Contents,) and it is better to take two Carats of silver less than one too much, and so the Rolls will remain the firmer and more intire, and there is no fear though somewhat of the Rolls were lost or torn off.
[Section. 12] You may also finde in a Gold (of which you intend to prove the red and white) that if you make the Assay-Proof, (as above demonstrated) then cut one Mark of the Gold more, and put it with its due of Lead without any other Cut) upon the Coppels, and let it go off with the Try-proof, then weigh the same Grain, and you will see what is gon off, and how much it comes out lighter, so much hath been red with it.
Thus you have the right and clear Instruction for Gold Proofs, and if you will follow it, you will do well, and thereby not be apt to err in your proofs.
To cut pieces for Treal.
The Carat weight must be small,
Assay proof▪
To make the Carat.
The Tryal of it.
To beat the little Rolls.
Disselving.
To sweeten or dulcify.
To neal the little Gold Rolls.
Coyned Gold.
To make the true Carats.
Another way to find red in Gold.