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. VI. How to prove light Coppers.

[Section. 1] POOR copper-Oars (especially the cop∣per Flints and copper-Glass which are in the Mountains or in light shiffer Mines) they must be proved thus; Take a common Proof of the Oar, grind it well, and weigh with thy Proof weight twenty or more centners, and draw it in a Vessel, so that therewith the light clay may be separated from the pure slick and copper Oars; weigh the slick which comes from it, thus, and mark how many centners yields a pound, that you may know how many centners of raw Oar (from the Rock or vein in the Mine) do yield a clean centner.

[ 2,] Weigh then two centners of such pure slick, and put them in an Assay-test, to be roasted in an Oven (as you have done with the copper Oars) but that the proof may not be false, (because the slick doth use to sparkle in the first setting of it into the great heat, especially if pibbles be among it,) therefore cover the Test wherein the weighed slick is, with another Test; let it remain thus covered till the slick glow well; then take off the upper Test, and roast the slick (as you are instructed before) and then grinde it very small, and divide it into two equal parts, and mingle one of them with the Fluss (ap∣pertaining to the copper Oars) and put it into a cruci∣ble, covered with Salt, and do as you have done above with the harsh copper Oars, and you will find in the bot∣tom of the crucible, a grain of copper: then weigh this with your Proof-weight, so you may know out of how

many centners or quantities of such raw, rocky or wash∣work you may make of a centner of black copper, which grain'd copper you may prove afterwards for Silver, and find the Content, and maist order thy matters ac∣cordingly.

[Section. 3] This proof upon poor mixt copper-Oars, I have put here because experience manifesteth, That the Copper Oars do not break throughout clean upon the Veins, but have much flint and subtil copper-glass mingled with them, yet in the washing they do willingly separate from it, and bring it into such a compass that one may know that all the rest of the Oars from those Veins may be wrought to good profit, which could not be, if they should be melted raw.

[Section. 4] Concerning the poor Shiffer which contains very little Copper, they cannot well be brought into compass, for they rise for the most part in the Water, and are fu∣gitives, although some do separate in the water, and af∣ford a slick, and thus they may be brought into com∣pass, and may be thus proved, and made to profit like the other Oars.

[Section. 5] Then the Copper-flint will stand apparently mixt and streamy, in some shiffers which are to be proved either raw or among others, or the shiffer apart whereby it may be found what copper the Shiffer doth yield, and the melting ordered accordingly.

[Section. 6] The other mixt copper-Oars (as Lasure Copper green, or brown rich copper-Oars) cannot be well separated in the water from their mixtures, for they are very light, and run not in weight, like the other flints, but go forth in the water, therefore such are first to be proved for Silver, if they have none (as commonly they are poor) then tis not much to try, but if they contain Sil∣ver, glow them hard, and suddenly quench them in cold water, then the insperged or mixt Copper Oars will

run together in little Grains (as above is signified of the Gold Oars) then wash and grind them small, and draw it into a slick, and when it separates, then you may in the great Work according to the quantity of slicks re∣gulate your self. But how these copper Oars are to be dryed in the little oven, you will be directed hereafter.