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. XVII. How Silver is to be proved for Gold.

[Section. 1] THAT I may not mix the Proving of Metals together, but give to every proof its due, and to write of every one apart, how it must be done: Know then if one would prove a goldish silver upon Gold, it must first be proved upon fine Silver, that one may find the right Content, both of the fine Silver and also of the fine Gold: Therefore when it is proved upon the fine (as I have taught in the Sil∣ver proof) then take the same proof Grains, beat them thin, glow them, and weigh a Mark of it with thy Penny∣weight, and dissolve the Silver in a little separating glass in Aqua fort. then there will remain a brown Gold-Calx: [Section. 2] pour off the Aqua fort. very gently, then take warm sweet water (as you have done before in the Gold Proof) and put it upon the Gold-Calx, and let it boil over the Coal-fire in a little Culbe or bottle: now when the Gold Calx hath setled it self again, then drain the water off, and put upon the Gold Calx two or three warm waters more, that thus the silvery water may be clean taken off from the Gold Calx, then put the Gold Calx clean out of the Culbe, into a glass pott, that nothing may remain, then drain the water very clean off from it, and bring the Gold Calx in the golden little Pot clean together, and if there be wetness about the Gold-Calx, then press it with a clean little cloth where 'tis made moist, and gently on

the end of one side, that the wetness may be suck'd in (only touch not the Gold Calx with the Cloth.)

[Section. 3] When this is done, then set the little golden Pot upon the Trevet in the Assay Oven, but not suddenly (that the Gold may not leap, and the proof become false) and glow out the Gold calx, so will it become fair, then put it again out of the golden little Pot into the inward Scale of the Proof-Ballance, and see how much it weighs according to the divided Penny-weight, with which you have weighed it, so you will have the Content; now how much a Mark of Silver containeth, I put this as an Example, for I have proved, That a Goldish silver or grain'd Gold, of this mixt Mark) hath contained 14 loths and a dram of fine Silver, and such fine Silver hath in a dram a penny-weight of Gold, then the Content in the Goldish Silver upon a Mark doth signify that it doth contain 13 loths, 3 drams, and three peny weight of fine silver, and one dram and one peny weight of Gold.

[Section. 4] Likewise in this manner one may also prove the fine Gold which is come from grained Silver, if one doth weigh a Mark of it, and dissolve it, and if the fine Mark in such a proof do contain one dram, one peny-weight, and one Heller of Gold, and is the Contents: and if a Mark of the grained Silver containeth 14 loths one dram be reckoned upon fine Silver, then the Mark will signify one dram, one peny, one heller of Gold, and of such proof it is counted, that by it the Gold is found a little less than the former, but I leave it to every ones pleasure to try and judge.

[ 5] Some Assayers have this Method, when they would prove a goldish grain'd Oar for Silver and Gold, then they weigh the grain'd Metal with their penny weight, and prove it upon fine Silver, (as 'tis usual) and they weigh in a grain such grain'd Metal after the mentioned weight (as at first) and dissolve it raw in Aqua fort.

[Section. 6] and as much then as they do find in Gold, they sub∣stract it from the fine-Silver, and this they count for the right proof to prove Silver upon Gold.

But that one may know that this their Proof is false and unjust, although somewhat more of Gold is to be found by it, therefore I will shew some Reasons why the same Gold is not so high in Fineness as the Gold which is separated out of the Proof of the fine Silver by Aqua fort.

First, although the Copper doth dissolve, yet the green Coppery water sets it self rather on the Gold than on the silvery water, and then the Copper which hath set it self cannot be brought off again so clean from the Gold, as from the tender silvery-water.

Secondly, Gold cometh higher out of the separation than when the silver is Coppery, upon which the Aqua fort. doth not work so easily, as on the fine Silver: Therefore no Separater of Gold doth take upon him to separate such Silver after such proof, but all the Silvers which he separates in Aqua fort. must first be burnt up∣on a Test.

[Section. 7] Thirdly, Although the first Process to prove the Goldish Silver upon Gold is the common way, and also the right Proof, by which the true Content is to be found. Nevertheless, I must further mention a singu∣lar proof (which is found upon such goldish silver and grain'd Work) by which, in the dissolution the little grains or small cut pieces of Silver will remain whole in the Aqua fort. (of what light Contents soever they be of Gold) and how small and subtil soever the grains be: also that one may number all the little grains of Gold af∣ter the number of the little pieces of Silver, how many there be laid in the Aqua fort. and no splitting will go off from it (as in the other proofs) yet if the grains should be weighed in, (also raw) the Gold will remain the bet∣ter

whole, but this proving is to be done thus, when you have weighed off the Silver put upon it a very weak Aqua fort. which the Silver cannot well touch, and put it in a Culbe to dissolve over a little Coal-fire (as is usual) and let it be very hot, that the Aqua fort. may work with great Bubbles, and almost boyl over, this dissolution do, so long until thy inweighed Silver be almost dissolved, but that it may have the better help, put (if the Silver be dissolved) a little more than half of new and a somewhat stronger Aqua fort. into the Culbe, and the Silver will dissolve it self clean out, and will split no more, although the second time, there be put to it, the stronger Aqua fort.) but what it doth will be done at first.

This is a fine way through which the Gold remain∣eth together in grains close, but 'twill have somewhat more time than the other common proof: there are also other wayes to such proofs, as follows.

Notes

• First Tryal.
• To dulcify it.
• To glow.
• A Second Tryal.
• A third way.
• Difference of the Proof.
• A Singular Dissolving.