Fleta minor the laws of art and nature, in knowing, judging, assaying, fining, refining and inlarging the bodies of confin'd metals : in two parts : the first contains assays of Lazarus Erckern, chief prover, or assay-master general of the empire of Germany, in V. books, orinally written by him in the Teutonick language and now translated into English ; the second contains essays on metallick words, as a dictionary to many pleasing discourses, by Sir John Pettus ... ; illustrated with 44 sculptures.

CHAP. XVI. How to prove the Aqua fort▪ and how much Gold it doth leave in the Proof.

[Section. 1] ALSO, if thou wilt prove an Aqua fort. how much is substracted in the Gold-Proof, * 1.1Take Gold which is cast divers times, through Antimony, and is brought to the highest: and make the proportion upon 24 carats▪ and weigh it also in two half Marks (as you have been instructed before) and multiply it by 3▪ then there will come upon every half Mark of fine Gold 36 carats of fine Silver, then put every half Mark of its propor∣tion

by it self, upon well neal▪d Coppels, let it go off to∣gether, weigh the grains off, and see whether they come alike, and beat them in slender Rolls, and put them in∣to separating Glasses, and put upon them so much A∣qua fort. as one doth use to take to a Gold-proof, as hath been shewn before in the Gold proof: then place it with an iron Trevet over a little Coal-fire: Let it dissolve, and put upon it the Second time fresh Aqua fort. set it over again; when now it is right, and well dissolved, pour the Aqua fort. on it, and make the Rolls with warm vvater very clean, and dry them, and glovv them in a little melting pot for Gold, and they vvill become fine, then weigh them one against the other, and if the Rolls be alike then the Proof is right; then lay them together, and against it thy whole mark: (after you have weigh∣ed it) and as the Golden Rolls do come out heavier, so much is to be substracted in the Gold-proof upon this one Mark of fine Gold.

[Section. 2] * 1.2Take this for an Example: I have weighed in two half Marks upon one Mark of fine Gold, and have par∣ted it vvith the Aqua fort. (as above is mentioned) and after the dissolving, dulcifying and glowing, then the two little Rolls have weighed one Mark or 24 carats and one grain and a half, so that the Aqua fort. hath left behind two grains, in the Proof, thus much is to be substracted in this Aqua fort. upon 42 carats.

[Section. 3] Know also that such as is kept back in the Aqua fort. * 1.3is nothing else but silver which the Aqua fort. could not draw out so clean, by which the Gold doth not become so very clean and fine, which is to be seen. If one let∣teth the Golden part go off with a little clean Lead upon a Coppel, to see how they become smaller or retain their weights. But if the Aqua fort. do leave its strength or spirits with the Gold, (as some do think) then the same could not remain nor consist upon the Coppels.

Out of which may be concluded, That by Aqua fort. fine Gold is made: But this is sure, That a good and well purified Aqua fort. bringeth the Gold in part∣ing (especially if the Gold Calx (as shall follow) hath been cleanly dulcified) to 23 Carats and 11 Grains. But it is not yet quite fine Gold, for the remainder with the Gold is nothing else (as is said before) than Silver: (as well in the parting the Gold, as in the Proof) else one may drive away what is left with the Bellows, and make it clean.

[Section. 4] But if you have no fine Gold, to the Proof of the Aqua fort. then take Hungarish Gold, whose Content * 1.4you know certainly, and make of the same Content the Divisions and Proportions, then you may find what is to be left behind of the Aqua fort. and how much is substracted of it: But the Gold which is cast through Antimony (as is before mentioned) is for such use much surer and better: And know, That the same Aqua fort. after the Distilling must be purified and settled, before you do prove or use it to the Gold-Proof, of which after∣wards an Instruction shall follow.

[Section. 5] * 1.5To all such proving you must have clean separating Glasses, Tunnels and little glass Pots for Gold to sweeten in, these are to be made of good Venetian Glass, and the brighter, whiter and clearer they are, the better it is, that the proofs may well be seen in them.

[Section. 6] But the Iron or Brazen Instrument, upon which the little separating Glass must stand, is to be made four foot∣ed, * 1.6that it may stand fast, and also with a little handle, by which it may be taken off, likewise another little foot or instrument of Copper or Iron, which must be flat, upon which is to be set the Golden little Pots (if one will have it set in the proof-Oven for the out-glowing) because this Proof is the finest, most glorious and lovely, therefore all

things pertaining to it must be made and prepared with all diligence and cleanliness.

Notes

• * 1.1

  The manner of Trying it.
• * 1.2

  Another way.
• * 1.3

  What the Remainder is.
• * 1.4

  Rules for it.
• * 1.5

  Separating Glass, and other Glass Instruments
• * 1.6

  An Instru∣ment for the Separating glass.