De Re Metallica, Translated from the First Latin Edition of 1556 - Georg Agricola

[Pg 219][1] We have but little record of anything which could be called "assaying" among the Greeks and Romans. The fact, however, that they made constant use of the touchstone (see [note 37, p. 252]) is sufficient proof that they were able to test the purity of gold and silver. The description of the touchstone by Theophrastus contains several references to "trial" by fire (see [note 37, p. 252]). They were adepts at metal working, and were therefore familiar with melting metals on a small scale, with the smelting of silver, lead, copper, and tin ores (see [note 1, p. 353]) and with the parting of silver and lead by cupellation. Consequently, it would not require much of an imaginative flight to conclude that there existed some system of tests of ore and metal values by fire. Apart from the statement of Theophrastus referred to, the first references made to anything which might fill the rôle of assaying are from the Alchemists, particularly Geber (prior to 1300), for they describe methods of solution, precipitation, distillation, fusing in crucibles, cupellation, and of the parting of gold and silver by acid and by sulphur, antimony, or cementation. However, they were not bent on [Pg 220]determining quantitative values, which is the fundamental object of the assayer's art, and all their discussion is shrouded in an obscure cloak of gibberish and attempted mysticism. Nevertheless, therein lies the foundation of many cardinal assay methods, and even of chemistry itself.

The first explicit records of assaying are the anonymous booklets published in German early in the 16th Century under the title Probierbüchlein. Therein the art is disclosed well advanced toward maturity, so far as concerns gold and silver, with some notes on lead and copper. We refer the reader to [Appendix B] for fuller discussion of these books, but we may repeat here that they are a collection of disconnected recipes lacking in arrangement, the items often repeated, and all apparently the inheritance of wisdom passed from father to son over many generations. It is obviously intended as a sort of reminder to those already skilled in the art, and would be hopeless to a novice. Apart from some notes in Biringuccio (Book III, Chaps. 1 and 2) on assaying gold and silver, there is nothing else prior to De Re Metallica. Agricola was familiar with these works and includes their material in this chapter. The very great advance which his account represents can only be appreciated by comparison, but the exhaustive publication of other works is foreign to the purpose of these notes. Agricola introduces system into the arrangement of his materials, describes implements, and gives a hundred details which are wholly omitted from the previous works, all in a manner which would enable a beginner to learn the art. Furthermore, the assaying of lead, copper, tin, quicksilver, iron, and bismuth, is almost wholly new, together with the whole of the argument and explanations. We would call the attention of students of the history of chemistry to the general oversight of these early 16th Century attempts at analytical chemistry, for in them lie the foundations of that science. The statement sometimes made that Agricola was the first assayer, is false if for no other reason than that science does not develop with such strides at any one human hand. He can, however, fairly be accounted as the author of the first proper text-book upon assaying. Those familiar with the art will be astonished at the small progress made since his time, for in his pages appear most of the reagents and most of the critical operations in the dry analyses of gold, silver, lead, copper, tin, bismuth, quicksilver, and iron of to-day. Further, there will be recognised many of the "kinks" of the art used even yet, such as the method of granulation, duplicate assays, the "assay ton" method of weights, the use of test lead, the introduction of charges in leaf lead, and even the use of beer instead of water to damp bone-ash.

The following table is given of the substances mentioned requiring some comment, and the terms adopted in this book, with notes for convenience in reference. The German terms are either from Agricola's Glossary of De Re Metallica, his Interpretatio, or the German Translation. We have retained the original German spelling. The fifth column refers to the page where more ample notes are given:—

Terms adopted.	Latin.	German.	Remarks.	Further Notes.
Alum	Alumen	Alaun	Either potassium or ammonia alum	p. [564]
Ampulla	Ampulla	Kolb	A distillation jar
Antimony	Stibium	Spiesglas	Practically always antimony sulphide	p. [428]
Aqua valens or aqua	Aqua valens	Scheidewasser	Mostly nitric acid	p. [439]
Argol	Feces vini siccae	Die weinheffen	Crude tartar	p. [234]
Ash of lead	Nigrum plumbum cinereum		Artificial lead sulphide	p. [237]
Ash of musk ivy (Salt made from)	Sal ex anthyllidis cinere factus	Salalkali	Mostly potash	p. [560]
Ashes which wool-dyers use	Cineres quo infectores lanarum		Mostly potash	p. [559]
Assay	Venas experiri	Probiren
Assay furnace	Fornacula	Probir ofen	"Little" furnace
Azure	Caeruleum	Lasur	Partly copper carbonate (azurite) partly silicate	p. [110]
[Pg 221]Bismuth	Plumbum Cinereum	Wismut	Bismuth	p. [433]
Bitumen	Bitumen	Bergwachs		p. [581]
Blast furnace	Prima fornax	Schmeltzofen
Borax	Chrysocolla ex nitro confecta; chrysocolla quam boracem nominant	Borras; Tincar		p. [560]
Burned alum	Alumen coctum	Gesottener alaun	Probably dehydrated alum	p. [565]
Cadmia (see [note 8, p. 112])			(1) Furnace accretions (2) Calamine (3) Zinc blende (4) Cobalt arsenical sulphides	p. [112]
Camphor	Camphora	Campffer		p. [238]
Chrysocolla called borax (see [borax])
Chrysocolla (copper mineral)	Chrysocolla	Berggrün und Schifergrün	Partly chrysocolla, partly malachite	p. [110]
Copper filings	Aeris scobs elimata	Kupferfeilich	Apparently finely divided copper metal	p. [233]
Copper flowers	Aeris flos	Kupferbraun	Cupric oxide	p. [538]
Copper scales	Aeris squamae	Kupfer hammerschlag oder kessel braun	Probably cupric oxide
Copper minerals (see [note 8, p. 109])
Crucible (triangular)	Catillus triangularis	Dreieckichtschirbe	See illustration	p. [229]
Cupel	Catillus cinereus	Capelle
Cupellation furnace	Secunda fornax	Treibherd
Flux	Additamentum	Zusetze		p. [232]
Furnace accretions	Cadmia fornacum	Mitlere und obere offenbrüche
Galena	Lapis plumbarius	Glantz	Lead sulphide	p. [110]
Glass-gall	Recrementum vitri	Glassgallen	Skimmings from glass melting	p. [235]
Grey antimony or stibium	Stibi or stibium	Spiesglas	Antimony sulphide, stibnite	p. [428]
Hearth-lead	Molybdaena	Herdplei	The saturated furnace bottoms from cupellation	p. [476]
Hoop (iron)	Circulus ferreus	Ring	A forge for crucibles	p. [226]
Iron filings	Ferri scobs elimata	Eisen feilich	Metallic iron
Iron scales	Squamae ferri	Eisen hammerschlag	Partly iron oxide
Iron slag	Recrementum ferri	Sinder
Lead ash	Cinis plumbi nigri	Pleiasche	Artificial lead sulphide	p. [237]
Lead granules	Globuli plumbei	Gekornt plei	Granulated lead
Lead ochre	Ochra plumbaria	Pleigeel	Modern massicot (PbO)	p. [232]
Lees of aqua which separates gold from silver	Feces aquarum quae aurum ab argento secernunt	Scheidewasser heffe	Uncertain	p. [234]
Dried lees of vinegar	Siccae feces aceti	Heffe des essigs	Argol	p. [234]
Dried lees of wine	Feces vini siccae	Wein heffen	Argol	p. [234]
[Pg 222]Limestone	Saxum calcis	Kalchstein
Litharge	Spuma argenti	Glette
Lye	Lixivium	Lauge durch asschen gemacht	Mostly potash	p. [233]
Muffle	Tegula	Muffel	Latin, literally "Roof-tile"
Operculum	Operculum	Helm oder alembick	Helmet or cover for a distillation jar
Orpiment	Auripigmentum	Operment	Yellow sulphide of arsenic (As₂S₃)	p. [111]
Pyrites	Pyrites	Kis	Rather a genus of sulphides, than iron pyrite in particular	p. [112]
Pyrites (Cakes from)	Panes ex pyrite conflati	Stein	Iron or Copper matte	p. [350]
Realgar	Sandaraca	Rosgeel	Red sulphide of arsenic (AsS)	p. [111]
Red lead	Minium	Menning	Pb₃O₄	p. [232]
Roasted copper	Aes ustum	Gebrandt kupffer	Artificial copper sulphide (?)	p. [233]
Salt	Sal	Saltz	NaCl	p. [233]
Salt (Rock)	Sal fossilis	Berg saltz	NaCl	p. [233]
Sal artificiosus	Sal artificiosus		A stock flux?	p. [236]
Sal ammoniac	Sal ammoniacus	Salarmoniac	NH₄Cl	p. [560]
Saltpetre	Halinitrum	Salpeter	KNO₃	p. [561]
Salt (refined)	Sal facticius purgatus		NaCl
Sal tostus	Sal tostus	Geröst saltz	Apparently simply heated or melted common salt	p. [233]
Sal torrefactus	Sal torrefactus	Geröst saltz		p. [233]
Salt (melted)	Sal liquefactus	Geflossen saltz	Melted salt or salt glass	p. [233]
Scorifier	Catillus fictilis	Scherbe
Schist	Saxum fissile	Schifer
Silver minerals (see [note 8, p. 108])
Slag	Recrementum	Schlacken
Soda	Nitrum		Mostly soda from Egypt, Na₂CO₃	p. [558]
Stones which easily melt	Lapides qui facile igni liquescunt	Flüs	Quartz and fluorspar	p. [380]
Sulphur	Sulfur	Schwefel		p. [579]
Tophus	Tophus	Topstein	Marl?	p. [233]
Touchstone	Coticula	Goldstein
Venetian glass	Venetianum vitrum
Verdigris	Aerugo	Grünspan oder Spanschgrün	Copper sub-acetate	p. [440]
Vitriol	Atramentum sutorium	Kupferwasser	Mostly FeSO₄	p. [572]
White schist	Saxum fissile album	Weisser schifer		p. [234]
Weights (see [Appendix]).

[Pg 224][2] Crudorum,—unbaked?

[3] This reference is not very clear. Apparently the names refer to the German terms probier ofen and windt ofen.

[Pg 226][4] Circulus. This term does not offer a very satisfactory equivalent, as such a furnace has no distinctive name in English. It is obviously a sort of forge for fusing in crucibles.

[Pg 230][5] Spissa,—"Dry." This term is used in contra-distinction to pingue, unctuous or "fatty."

[Pg 232][6] Additamenta,—"Additions." Hence the play on words.

We have adopted "flux" because the old English equivalent for all these materials was "flux," although in modern nomenclature the term is generally restricted to those substances which, by chemical combination in the furnace, lower the melting point of some of the charge. The "additions" of Agricola, therefore, include reducing, oxidizing, sulphurizing, desulphurizing, and collecting agents as well as fluxes. A critical examination of the fluxes mentioned in the next four pages gives point to the Author's assertion that "some are of a very complicated nature." However, anyone of experience with home-taught assayers has come in contact with equally extraordinary combinations. The four orders of "additions" enumerated are quite impossible to reconcile from a modern metallurgical point of view.