Chapter XIX: Book VII (3)

the 1st = 8 _unciae_ = 1 _bes_.
" 2nd = 4 "
" 3rd = 2 "
" 4th = 1 " or 4 _sicilici_.
" 5th = 2 _sicilici_.
" 6th = 1 _sicilicus_.
" 7th = 18 _siliquae_.
" 8th = 9 "
" 9th = 6 "
" 10th = 3 "
" 11th = 2 "
" 12th = 1 "

Since the Venetians divide the _bes_ into eleven hundred and fifty-two _siliquae_, or two hundred and eighty-eight units of 4 _siliquae_ each, into which number our people also divide the _bes_, they thus make the same number of _siliquae_, and both agree, even though the Venetians divide the _bes_ into smaller divisions.

This, then, is the system of weights, both of the greater and the lesser kinds, which metallurgists employ, and likewise the system of the lesser weights which coiners and merchants employ, when they are assaying metals and coined money. The _bes_ of the larger weight with which they provide themselves when they weigh large masses of these things, I have explained in my work _De Mensuris et Ponderibus_, and in another book, _De Precio Metallorum et Monetis_.

There are three small balances by which we weigh ore, metals, and fluxes. The first, by which we weigh lead and fluxes, is the largest among these smaller balances, and when eight _unciae_ (of the greater weights) are placed in one of its pans, and the same number in the other, it sustains no damage. The second is more delicate, and by this we weigh the ore or the metal, which is to be assayed; this is well able to carry one _centumpondium_ of the lesser weights in one pan, and in the other, ore or metal as heavy as that weight. The third is the most delicate, and by this we weigh the beads of gold or silver, which, when the assay is completed, settle in the bottom of the cupel. But if anyone weighs lead in the second balance, or an ore in the third, he will do them much injury.

Whatsoever small amount of metal is obtained from a _centumpondium_ of the lesser weights of ore or metal alloy, the same greater weight of metal is smelted from a _centumpondium_ of the greater weight of ore or metal alloy.

END OF BOOK VII.

FOOTNOTES:

[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 _role_ 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 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 _Probierbuechlein_. 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 Latin. German. Remarks. Further
adopted. Notes.

Alum _Alumen_ _Alaun_ Either potassium p. 564
or ammonia alum

Ampulla _Ampulla_ _Kolb_ A distillation jar

Antimony _Stibium_ _Spiesglas_ Practically always p. 428
antimony sulphide

_Aqua valens_ _Aqua valens_ _Scheidewasser_ Mostly nitric acid p. 439
or _aqua_

Argol _Feces vini _Die Crude tartar p. 234
siccae_ weinheffen_

Ash of lead _Nigrum Artificial lead p. 237
plumbum sulphide
cinereum_

Ash of musk ivy _Sal ex _Salalkali_ Mostly potash p. 560
(Salt made anthyllidis
from) cinere factus_

Ashes which _Cineres quo Mostly potash p. 559
wool-dyers use infectores
lanarum
utuntur_

Assay _Venas experiri_ _Probiren_

Assay furnace _Fornacula_ _Probir ofen_ "Little" furnace

Azure _Caeruleum_ _Lasur_ Partly copper p. 110
carbonate
(azurite)
partly silicate

Bismuth _Plumbum _Wismut_ _Bismuth_ p. 433
Cinereum_

Bitumen _Bitumen_ _Bergwachs_ p. 581

Blast furnace _Prima fornax_ _Schmeltzofen_

Borax _Chrysocolla ex _Borras; Tincar_ p. 560
nitro
confecta;
chrysocolla
quam boracem
nominant_

Burned alum _Alumen coctum_ _Gesottener Probably p. 565
alaun_ dehydrated alum

_Cadmia_ (1) Furnace p. 112
(see note accretions (2)
8, p. 112) Calamine (3) Zinc
blende (4) Cobalt
arsenical sulphides

Camphor _Camphora_ _Campffer_ p. 238

Chrysocolla
called borax
(see borax)

Chrysocolla _Chrysocolla_ _Berggruen und Partly p. 110
(copper Schifergruen_ chrysocolla,
mineral) partly malachite

Copper filings _Aeris scobs _Kupferfeilich_ Apparently finely p. 233
elimata_ divided copper
metal

Copper flowers _Aeris flos_ _Kupferbraun_ Cupric oxide p. 538

Copper scales _Aeris squamae_ _Kupfer Probably cupric
hammerschlag oxide
oder kessel
braun_

Copper
minerals (see
note 8,
p. 109)

Crucible _Catillus _Dreieckicht- See illustration p. 229
(triangular) triangularis_ schirbe_

Cupel _Catillus _Capelle_
cinereus_

Cupellation _Secunda _Treibherd_
furnace fornax_

Flux _Additamentum_ _Zusetze_ p. 232

Furnace _Cadmia _Mitlere und
accretions fornacum_ obere
offenbrueche_

Galena _Lapis _Glantz_ Lead sulphide p. 110
plumbarius_

Glass-gall _Recrementum _Glassgallen_ Skimmings from p. 235
vitri_ glass melting

Grey antimony or _Stibi_ or _Spiesglas_ Antimony sulphide, p. 428
stibium _stibium_ stibnite

Hearth-lead _Molybdaena_ _Herdplei_ The saturated p. 476
furnace bottoms
from cupellation

Hoop (iron) _Circulus _Ring_ A forge for p. 226
ferreus_ crucibles

Iron filings _Ferri scobs _Eisen feilich_ Metallic iron
elimata_

Iron scales _Squamae ferri_ _Eisen Partly iron oxide
hammerschlag_

Iron slag _Recrementum _Sinder_
ferri_

Lead ash _Cinis plumbi _Pleiasche_ Artificial lead p. 237
nigri_ sulphide

Lead granules _Globuli _Gekornt plei_ Granulated lead
plumbei_

Lead ochre _Ochra _Pleigeel_ Modern massicot p. 232
plumbaria_ (PbO)

Lees of _aqua_ _Feces aquarum _Scheidewasser Uncertain p. 234
which separates quae aurum ab heffe_
gold from argento
silver secernunt_

Dried lees of _Siccae feces _Heffe des Argol p. 234
vinegar aceti_ essigs_

Dried lees of _Feces vini _Wein heffen_ Argol p. 234
wine siccae_

Limestone _Saxum calcis_ _Kalchstein_

Litharge _Spuma argenti_ _Glette_

Lye _Lixivium_ _Lauge durch Mostly potash p. 233
asschen
gemacht_

Muffle _Tegula_ _Muffel_ Latin, literally
"Roof-tile"

Operculum _Operculum_ _Helm oder Helmet or cover
alembick_ for a distillation
jar

Orpiment _Auripigmentum_ _Operment_ Yellow sulphide p. 111
of arsenic
(As_{2}S_{3})

Pyrites _Pyrites_ _Kis_ Rather a genus p. 112
of sulphides,
than iron
pyrite in
particular

Pyrites (Cakes _Panes ex _Stein_ Iron or Copper p. 350
from) pyrite matte
conflati_

Realgar _Sandaraca_ _Rosgeel_ Red sulphide of p. 111
arsenic (AsS)

Red lead _Minium_ _Menning_ Pb_{3}O_{4} p. 232

Roasted copper _Aes ustum_ _Gebrandt Artificial p. 233
kupffer_ copper
sulphide (?)

Salt _Sal_ _Saltz_ NaCl p. 233

Salt (Rock) _Sal fossilis_ _Berg saltz_ NaCl p. 233

_Sal _Sal A stock flux? p. 236
artificiosus_ artificiosus_

Sal ammoniac _Sal _Salarmoniac_ NH_{4}Cl p. 560
ammoniacus_

Saltpetre _Halinitrum_ _Salpeter_ KNO_{3} p. 561

Salt (refined) _Sal facticius NaCl
purgatus_

_Sal tostus_ _Sal tostus_ _Geroest saltz_ Apparently p. 233
simply heated or
melted common
salt

_Sal _Sal _Geroest saltz_ p. 233
torrefactus_ torrefactus_

Salt (melted) _Sal _Geflossen Melted salt or p. 233
liquefactus_ saltz_ salt glass

Scorifier _Catillus _Scherbe_
fictilis_

Schist _Saxum fissile_ _Schifer_

Silver minerals
(see note 8,
p. 108)

Slag _Recrementum_ _Schlacken_

Soda _Nitrum_ Mostly soda from p. 558
Egypt,
Na_{2}CO_{3}

Stones which _Lapides qui _Flues_ Quartz and p. 380
easily melt facile igni fluorspar
liquescunt_

Sulphur _Sulfur_ _Schwefel_ p. 579

_Tophus_ _Tophus_ _Topstein_ Marl(?) p. 233

Touchstone _Coticula_ _Goldstein_

Venetian glass _Venetianum
vitrum_

Verdigris _Aerugo _Gruenspan_ Copper p. 440
oder sub-acetate
Spanschgruen_

Vitriol _Atramentum _Kupferwasser_ Mostly FeSO_{4} p. 572
sutorium_

White schist _Saxum fissile _Weisser p. 234
album_ schifer_

Weights (see
Appendix).

[2] _Crudorum_,--unbaked?

[3] This reference is not very clear. Apparently the names refer to the German terms _probier ofen_ and _windt ofen_.

[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.

[5] _Spissa_,--"Dry." This term is used in contra-distinction to _pingue_, unctuous or "fatty."

[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.

[7] _Minium secundarium_. (_Interpretatio_,--_menning_. Pb_{3}O_{4}). Agricola derived his Latin term from Pliny. There is great confusion in the ancient writers on the use of the word _minium_, for prior to the Middle Ages it was usually applied to vermilion derived from cinnabar. Vermilion was much adulterated with red-lead, even in Roman times, and finally in later centuries the name came to be appropriated to the lead product. Theophrastus (103) mentions a substitute for vermilion, but, in spite of commentators, there is no evidence that it was red-lead. The first to describe the manufacture of real red-lead was apparently Vitruvius (VII, 12), who calls it _sandaraca_ (this name was usually applied to red arsenical sulphide), and says: "White-lead is heated in a furnace and by the force of the fire becomes red lead. This invention was the result of observation in the case of an accidental fire, and by the process a much better material is obtained than from the mines." He describes _minium_ as the product from cinnabar. Dioscorides (V, 63), after discussing white-lead, says it may be burned until it becomes the colour of _sandaracha_, and is called _sandyx_. He also states (V, 69) that those are deceived who consider cinnabar to be the same as _minium_, for _minium_ is made in Spain out of stone mixed with silver sands. Therefore he is not in agreement with Vitruvius and Pliny on the use of the term. Pliny (XXXIII, 40) says: "These barren stones (apparently lead ores barren of silver) may be recognised by their colour; it is only in the furnace that they turn red. After being roasted it is pulverized and is _minium secundarium_. It is known to few and is very inferior to the natural kind made from those sands we have mentioned (_cinnabar_). It is with this that the genuine _minium_ is adulterated in the works of the Company." This proprietary company who held a monopoly of the Spanish quicksilver mines, "had many methods of adulterating it (_minium_)--a source of great plunder to the Company." Pliny also describes the making of red lead from white.

[8] _Ochra plumbaria_. (_Interpretatio_,--_pleigeel_; modern German,--_Bleigelb_). The German term indicates that this "Lead Ochre," a form of PbO, is what in the English trade is known as _massicot_, or _masticot_. This material can be a partial product from almost any cupellation where oxidation takes place below the melting point of the oxide. It may have been known to the Ancients among the various species into which they divided litharge, but there is no valid reason for assigning to it any special one of their terms, so far as we can see.

[9] There are four forms of copper named as re-agents by Agricola:

Copper filings _Aeris scobs elimata._
Copper scales _Aeris squamae._
Copper flowers _Aeris flos._
Roasted copper _Aes ustum._

The first of these was no doubt finely divided copper metal; the second, third, and fourth were probably all cupric oxide. According to Agricola (_De Nat. Fos._, p. 352), the scales were the result of hammering the metal; the flowers came off the metal when hot bars were quenched in water, and a third kind were obtained from calcining the metal. "Both flowers (_flos_) and hammer-scales (_squama_) have the same properties as _crematum_ copper.... The particles of flower copper are finer than scales or _crematum_ copper." If we assume that the verb _uro_ used in _De Re Metallica_ is of the same import as _cremo_ in the _De Natura Fossilium_, we can accept this material as being merely cupric oxide, but the _aes ustum_ of Pliny--Agricola's usual source of technical nomenclature--is probably an artificial sulphide. Dioscorides (V, 47), who is apparently the source of Pliny's information, says:--"Of _chalcos cecaumenos_, the best is red, and pulverized resembles the colour of cinnabar; if it turns black, it is over-burnt. It is made from broken ship nails put into a rough earthen pot, with alternate layers of equal parts of sulphur and salt. The opening should be smeared with potter's clay and the pot put in the furnace until it is thoroughly heated," etc. Pliny (XXXIV, 23) states: "Moreover Cyprian copper is roasted in crude earthen pots with an equal amount of sulphur; the apertures of the pots are well luted, and they are kept in the furnace until the pot is thoroughly heated. Some add salt, others use _alumen_ instead of sulphur, others add nothing, but only sprinkle it with vinegar."

[10] The reader is referred to note 6, p. 558, for more ample discussion of the alkalis. Agricola gives in this chapter four substances of that character:

Soda (_nitrum_). Lye. "Ashes which wool-dyers use." "Salt made
from the ashes of musk ivy."

The last three are certainly potash, probably impure. While the first might be either potash or soda, the fact that the last three are mentioned separately, together with other evidence, convinces us that by the first is intended the _nitrum_ so generally imported into Europe from Egypt during the Middle Ages. This imported salt was certainly the natural bicarbonate, and we have, therefore, used the term "soda."

[11] In this chapter are mentioned seven kinds of common salt:

Salt _Sal._
Rock salt _Sal fossilis._
"Made" salt _Sal facticius._
Refined salt _Sal purgatius._
Melted salt _Sal liquefactus._

And in addition _sal tostus_ and _sal torrefactus_. _Sal facticius_ is used in distinction from rock-salt. The melted salt would apparently be salt-glass. What form the _sal tostus_ and _sal torrefactus_ could have we cannot say, however, but they were possibly some form of heated salt; they may have been combinations after the order of _sal artificiosus_ (see p. 236).

[12] "Stones which easily melt in hot furnaces and sand which is made from them" (_lapides qui in ardentibus fornacibus facile liquescunt arenae ab eis resolutae_). These were probably quartz in this instance, although fluorspar is also included in this same genus. For fuller discussion see note on p. 380.

[13] _Tophus_. (_Interpretatio_, _Toffstein oder topstein_). According to Dana (Syst. of Min., p. 678), the German _topfstein_ was English potstone or soapstone, a magnesian silicate. It is scarcely possible, however, that this is what Agricola meant by this term, for such a substance would be highly infusible. Agricola has a good deal to say about this mineral in _De Natura Fossilium_ (p. 189 and 313), and from these descriptions it would seem to be a tufaceous limestone of various sorts, embracing some marls, stalagmites, calcareous sinter, etc. He states: "Generally fire does not melt it, but makes it harder and breaks it into powder. Tophus is said to be a stone found in caverns, made from the dripping of stone juice solidified by cold ... sometimes it is found containing many shells, and likewise the impressions of alder leaves; our people make lime by burning it." Pliny, upon whom Agricola depends largely for his nomenclature, mentions such a substance (XXXVI, 48): "Among the multitude of stones there is _tophus_. It is unsuitable for buildings, because it is perishable and soft. Still, however, there are some places which have no other, as Carthage, in Africa. It is eaten away by the emanations from the sea, crumbled to dust by the wind, and washed away by the rain." In fact, _tophus_ was a wide genus among the older mineralogists, Wallerius (_Meditationes Physico-Chemicae De Origine Mundi_, Stockholm, 1776, p. 186), for instance, gives 22 varieties. For the purposes for which it is used we believe it was always limestone of some form.

[14] _Saxum fissile album._ (_The Interpretatio_ gives the German as _schifer_). Agricola mentions it in _Bermannus_ (459), in _De Natura Fossilium_ (p. 319), but nothing definite can be derived from these references. It appears to us from its use to have been either a quartzite or a fissile limestone.

[15] Argol (_Feces vini siccae_,--"Dried lees of wine." Germ. trans. gives _die wein heffen_, although the usual German term of the period was _weinstein_). The lees of wine were the crude tartar or argols of commerce and modern assayers. The argols of white wine are white, while they are red from red wine. The white argol which Agricola so often specifies would have no special excellence, unless it may be that it is less easily adulterated. Agricola (_De Nat. Fos._, p. 344) uses the expression "_Fex vini sicca_ called _tartarum_"--one of the earliest appearances of the latter term in this connection. The use of argol is very old, for Dioscorides (1st Century A.D.) not only describes argol, but also its reduction to impure potash. He says (V, 90): "The lees (_tryx_) are to be selected from old Italian wine; if not, from other similar wine. Lees of vinegar are much stronger. They are carefully dried and then burnt. There are some who burn them in a new earthen pot on a large fire until they are thoroughly incinerated. Others place a quantity of the lees on live coals and pursue the same method. The test as to whether it is completely burned, is that it becomes white or blue, and seems to burn the tongue when touched. The method of burning lees of vinegar is the same.... It should be used fresh, as it quickly grows stale; it should be placed in a vessel in a secluded place." Pliny (XXIII, 31) says: "Following these, come the lees of these various liquids. The lees of wine (_vini faecibus_) are so powerful as to be fatal to persons on descending into the vats. The test for this is to let down a lamp, which, if extinguished, indicates the peril.... Their virtues are greatly increased by the action of fire." Matthioli, commenting on this passage from Dioscorides in 1565, makes the following remark (p. 1375): "The precipitate of the wine which settles in the casks of the winery forms stone-like crusts, and is called by the works-people by the name _tartarum_." It will be seen above that these lees were rendered stronger by the action of fire, in which case the tartar was reduced to potassium carbonate. The _weinstein_ of the old German metallurgists was often the material lixiviated from the incinerated tartar.

Dried lees of vinegar (_siccae feces aceti_; _Interpretatio_, _die heffe des essigs_). This would also be crude tartar. Pliny (XXIII, 32) says: "The lees of vinegar (_faex aceti_); owing to the more acrid material are more aggravating in their effects.... When combined with _melanthium_ it heals the bites of dogs and crocodiles."

[16] Dried lees of _aqua_ which separates gold and silver. (_Siccae feces aquarum quae aurum ab argento secernunt_. German translation, _Der scheidwasser heffe_). There is no pointed description in Agricola's works, or in any other that we can find, as to what this material was. The "separating _aqua_" was undoubtedly nitric acid (see p. 439, Book X). There are two precipitates possible, both referred to as _feces_,--the first, a precipitate of silver chloride from clarifying the _aqua valens_, and the second, the residues left in making the acid by distillation. It is difficult to believe that silver chloride was the _feces_ referred to in the text, because such a precipitate would be obviously misleading when used as a flux through the addition of silver to the assays, too expensive, and of no merit for this purpose. Therefore one is driven to the conclusion that the _feces_ must have been the residues left in the retorts when nitric acid was prepared. It would have been more in keeping with his usual mode of expression, however, to have referred to this material as a _residuus_. The materials used for making acid varied greatly, so there is no telling what such a _feces_ contained. A list of possibilities is given in note 8, p. 443. In the main, the residue would be undigested vitriol, alum, saltpetre, salt, etc., together with potassium, iron, and alum sulphates. The _Probierbuechlin_ (p. 27) also gives this re-agent under the term _Toden kopff das ist schlam oder feces auss dem scheydwasser_.

[17] _Recrementum vitri_. (_Interpretatio_, _Glassgallen_). Formerly, when more impure materials were employed than nowadays, the surface of the mass in the first melting of glass materials was covered with salts, mostly potassium and sodium sulphates and chlorides which escaped perfect vitrification. This "slag" or "_glassgallen_" of Agricola was also termed _sandiver_.

[18] The whole of this expression is "_candidus, candido_." It is by no means certain that this is tin, for usually tin is given as _plumbum candidum_.

[19] _Sal artificiosus_. These are a sort of stock fluxes. Such mixtures are common in all old assay books, from the _Probierbuechlin_ to later than John Cramer in 1737 (whose Latin lectures on Assaying were published in English under the title of "Elements of the Art of Assaying Metals," London, 1741). Cramer observes (p. 51) that: "Artificers compose a great many fluxes with the above-mentioned salts and with the reductive ones; nay, some use as many different fluxes as there are different ores and metals; all which, however, we think needless to describe. It is better to have explained a few of the simpler ones, which serve for all the others, and are very easily prepared, than to tire the reader with confused compositions: and this chiefly because unskilled artificers sometimes attempt to obtain with many ingredients of the same nature heaped up beyond measure, and with much labour, though not more properly and more securely, what might have been easily effected, with one only and the same ingredient, thus increasing the number, not at all the virtue of the things employed. Nevertheless, if anyone loves variety, he may, according to the proportions and cautions above prescribed, at his will chuse among the simpler kinds such as will best suit his purpose, and compose a variety of fluxes with them."

[20] This operation apparently results in a coating to prevent the deflagration of the saltpetre--in fact, it might be permitted to translate _inflammatur_ "deflagrate," instead of kindle.

[21] The results which would follow from the use of these "fluxes" would obviously depend upon the ore treated. They can all conceivably be successful. Of these, the first is the lead-glass of the German assayers--a flux much emphasized by all old authorities, including Lohneys, Ercker and Cramner, and used even yet. The "powerful flux" would be a reducing, desulphurizing, and an acid flux. The "more powerful" would be a basic flux in which the reducing action of the argols would be largely neutralised by the nitre. The "still more powerful" would be a strongly sulphurizing basic flux, while the "most powerful" would be a still more sulphurizing flux, but it is badly mixed as to its oxidation and basic properties. (See also note 19 on _sal artificiosus_).

[22] Lead ash (_Cinis Plumbi_. Glossary, _Pleyasch_).--This was obviously, from the method of making, an artificial lead sulphide.

[23] Ashes of lead (_Nigri plumbi cinis_). This, as well as lead ash, was also an artificial lead sulphide. Such substances were highly valued by the Ancients for medicinal purposes. Dioscorides (V, 56) says: "Burned lead (_Molybdos cecaumenos_) is made in this way: Sprinkle sulphur over some very thinnest lead plates and put them into a new earthen pot, add other layers, putting sulphur between each layer until the pot is full; set it alight and stir the melted lead with an iron rod until it is entirely reduced to ashes and until none of the lead remains unburned. Then take it off, first stopping up your nose, because the fumes of burnt lead are very injurious. Or burn the lead filings in a pot with sulphur as aforesaid." Pliny (XXXIV., 50) gives much the same directions.

[24] Camphor (_camphora_). This was no doubt the well-known gum. Agricola, however, believed that camphor (_De Nat. Fossilium_, p. 224) was a species of bitumen, and he devotes considerable trouble to the refutation of the statements by the Arabic authors that it was a gum. In any event, it would be a useful reducing agent.

[25] Inasmuch as orpiment and realgar are both arsenical sulphides, the use of iron "slag," if it contains enough iron, would certainly matte the sulphur and arsenic. Sulphur and arsenic are the "juices" referred to (see note 4, p. 1). It is difficult to see the object of preserving the antimony with such a sulphurizing "addition," unless it was desired to secure a regulus of antimony alone from a given antimonial ore.

[26] The lead free from silver, called _villacense_, was probably from Bleyberg, not far from Villach in Upper Austria, this locality having been for centuries celebrated for its pure lead. These mines were worked prior to, and long after, Agricola's time.

[27] This method of proportionate weights for assay charges is simpler than the modern English "assay ton," both because of the use of 100 units in the standard of weight (the _centumpondium_), and because of the lack of complication between the Avoirdupois and Troy scales. For instance, an ore containing a _libra_ of silver to the _centumpondium_ would contain 1/100th part, and the same ratio would obtain, no matter what the actual weight of a _centumpondium_ of the "lesser weight" might be. To follow the matter still further, an _uncia_ being 1/1,200 of a _centumpondium_, if the ore ran one "_uncia_ of the lesser weight" to the "_centumpondium_ of the lesser weight," it would also run one actual _uncia_ to the actual _centumpondium_; it being a matter of indifference what might be the actual weight of the _centumpondium_ upon which the scale of lesser weights is based. In fact Agricola's statement (p. 261) indicates that it weighed an actual _drachma_. We have, in some places, interpolated the expressions "lesser" and "greater" weights for clarity.

This is not the first mention of this scheme of lesser weights, as it appears in the _Probierbuechlein_ (1500? see Appendix B) and Biringuccio (1540). For a more complete discussion of weights and measures see Appendix C. For convenience, we repeat here the Roman scale, although, as will be seen in the Appendix, Agricola used the Latin terms in many places merely as nomenclature equivalents of the old German scale.

Ozs.
dwts.
Troy gr.
Grains. per short ton.
1 _Siliqua_ 2.87 Per _Centumpondium_ 0 3 9
6 _Siliquae_ = 1 _Scripulum_ 17.2 " " 1 0 6
4 _Scripula_ = 1 _Sextula_ 68.7 " " 4 1 0
6 _Sextulae_ = 1 _Uncia_ 412.2 " " 24 6 2
12 _Unciae_ = 1 _Libra_ 4946.4 " " 291 13 8
100 _Librae_ = 1 _Centumpondium_ 494640.0

However Agricola may occasionally use

16 _Unciae_ = 1 _Libra_ 6592.0 (?)
100 _Librae_ = 1 _Centumpondium_ 659200.0 (?)

Also

Oz.
dwts.
gr.
per short ton.
1 _Scripulum_ 17.2 Per _Centumpondium_ 1 0 6
3 _Scripula_ = 1 _Drachma_ 51.5 " " 3 0 19
2 _Drachmae_ = 1 _Sicilicus_ 103.0 " " 6 1 15
4 _Sicilici_ = 1 _Uncia_ 412.2 " " 24 6 12
8 _Unciae_ = 1 _Bes_ 3297.6 " " 194 12 0

[28] The amalgamation of gold ores is fully discussed in note 12, p. 297.

[29] For discussion of the silver ores, see note 8, p. 108. _Rudis_ silver was a fairly pure silver mineral, the various coloured silvers were partly horn-silver and partly alteration products.

[30] It is difficult to see why copper scales (_squamae aeris_--copper oxide?) are added, unless it be to collect a small ratio of copper in the ore. This additional copper is not mentioned again, however. The whole of this statement is very confused.

[31] This old story runs that Hiero, King of Syracuse, asked Archimedes to tell him whether a crown made for him was pure gold or whether it contained some proportion of silver. Archimedes is said to have puzzled over it until he noticed the increase in water-level upon entering his bath. Whereupon he determined the matter by immersing bars of pure gold and pure silver, and thus determining the relative specific weights. The best ancient account of this affair is to be found in Vitruvius, IX, Preface. The story does not seem very probable, seeing that Theophrastus, who died the year Archimedes was born, described the touchstone in detail, and that it was of common knowledge among the Greeks before (see note 37). In any event, there is not sufficient evidence in this story on which to build the conclusion of Meyer (Hist. of Chemistry, p. 14) and others, that, inasmuch as Archimedes was unable to solve the problem until his discovery of specific weights, therefore the Ancients could not part gold and silver. The probability that he did not want to injure the King's jewellery would show sufficient reason for his not parting these metals. It seems probable that the Ancients did part gold and silver by cementation. (See note on p. 458).

[32] The Alchemists (with whose works Agricola was familiar--_vide_ preface) were the inventors of nitric acid separation. (See note on p. 460).

[33] Parting gold and silver by nitric acid is more exhaustively discussed in Book X. and note 10, p. 443.

[34] The lesser weights, probably.

[35] Lead and Tin seem badly mixed in this paragraph.

[36] It is not clear what is added.

[37] HISTORICAL NOTE ON TOUCHSTONE. (_Coticula_. _Interpretatio_,--_Goldstein_). Theophrastus is, we believe, the first to describe the touchstone, although it was generally known to the Greeks, as is evidenced by the metaphors of many of the poets,--Pindar, Theognis, Euripides, etc. The general knowledge of the constituents of alloys which is implied, raises the question as to whether the Greeks did not know a great deal more about parting metals, than has been attributed to them. Theophrastus says (78-80): "The nature of the stone which tries gold is also very wonderful, as it seems to have the same power with fire; which is also a test of that metal. Some people have for this reason questioned the truth of this power in the stone, but their doubts are ill-founded, for this trial is not of the same nature or made in the same manner as the other. The trial by fire is by the colour and by the quantity lost by it; but that by the stone is made only by rubbing the metal on it; the stone seeming to have the power to receive separately the distinct particles of different metals. It is said also that there is a much better kind of this stone now found out, than that which was formerly used; insomuch that it now serves not only for the trial of refined gold, but also of copper or silver coloured with gold; and shows how much of the adulterating matter by weight is mixed with gold; this has signs which it yields from the smallest weight of the adulterating matter, which is a grain, from thence a colybus, and thence a quadrans or semi-obolus, by which it is easy to distinguish if, and in what degree, that metal is adulterated. All these stones are found in the River Tmolus; their texture is smooth and like that of pebbles; their figure broad, not round; and their bigness twice that of the common larger sort of pebbles. In their use in the trial of metals there is a difference in power between their upper surface, which has lain toward the sun, and their under, which has been to the earth; the upper performing its office the more nicely; and this is consonant to reason, as the upper part is dryer; for the humidity of the other surface hinders its receiving so well the particles of metals; for the same reason also it does not perform its office as well in hot weather as in colder, for in the hot it emits a kind of humidity out of its substance, which runs all over it. This hinders the metalline particles from adhering perfectly, and makes mistakes in the trials. This exudation of a humid matter is also common to many other stones, among others, to those of which statues are made; and this has been looked on as peculiar to the statue." (Based on Hill's trans.) This humid "exudation of fine-grained stones in summer" would not sound abnormal if it were called condensation. Pliny (XXXIII, 43) says: "The mention of gold and silver should be accompanied by that of the stone called _coticula_. Formerly, according to Theophrastus, it was only to be found in the river Tmolus but now found in many parts, it was found in small pieces never over four inches long by two broad. That side which lay toward the sun is better than that toward the ground. Those experienced with the _coticula_ when they rub ore (_vena_) with it, can at once say how much gold it contains, how much silver or copper. This method is so accurate that they do not mistake it to a scruple." This purported use for determining values of _ore_ is of about Pliny's average accuracy. The first detailed account of touch-needles and their manner of making, which we have been able to find, is that of the _Probierbuechlein_ (1527? see Appendix) where many of the tables given by Agricola may be found.

[38] _De Natura Fossilium_ (p. 267) and _De Ortu et Causis Subterraneorum_ (p. 59). The author does not add any material mineralogical information to the quotations from Theophrastus and Pliny given above.

[39] In these tables Agricola has simply adopted Roman names as equivalents of the old German weights, but as they did not always approximate in proportions, he coined terms such as "units of 4 _siliquae_," etc. It might seem more desirable to have introduced the German terms into this text, but while it would apply in this instance, as we have discussed on p. 259, the actual values of the Roman weights are very different from the German, and as elsewhere in the book actual Roman weights are applied, we have considered it better to use the Latin terms consistently throughout. Further, the obsolete German would be to most readers but little improvement upon the Latin. For convenience of readers we set out the various scales as used by Agricola, together with the German:--

ROMAN SCALE. OLD GERMAN SCALE.
6 _Siliquae_ = 1 _Scripulum_ 3 _Grenlin_ = 1 _Gran_
4 _Scripula_ = 1 _Sextula_ 4 _Gran_ = 1 _Krat_
2 _Sextulae_ = 1 _Duella_ 24 _Kratt_ = 1 _Mark_
24 _Duellae_ = 1 _Bes_ or
24 _Grenlin_ = 1 "_Nummus_"
12 "_Nummi_" = 1 _Mark_

Also the following scales are applied to fineness by Agricola:--

3 _Scripula_ = 1 _Drachma_ 4 _Pfennige_ = 1 _Quintlein_
2 _Drachmae_ = 1 _Sicilicus_ 4 _Quintlein_ = 1 _Loth_
2 _Sicilici_ = 1 _Semuncia_ 16 _Loth_ = 1 _Mark_
16 _Semunciae_ = 1 _Bes_

The term "_nummus_," a coin, given above and in the text, appears in the German translation as _pfennig_ as applied to both German scales, but as they are of different values, we have left Agricola's adaptation in one scale to avoid confusion. The Latin terms adopted by Agricola are given below, together with the German:--

Number in one Value in
Roman Term. German Term. Mark or Bes. _Siliquae_.

_Siliqua_ 1152 1

"Unit of 4 _Siliquae_" _Grenlin_ 288 4

_Pfennig_ 256 --

_Scripulum_ _Scruple_ (?) 192 6

_Semi-sextula_ _Gran_ 96 12

_Drachma_ _Quintlein_ 64 18

_Sextula_ _Halb Krat_ 48 24

_Sicilicus_ _Halb Loth_ 32 36

_Duella_ _Krat_ 24 48

_Semuncia_ _Loth_ 16 72

"_Unit of 5 Drachmae "_Nummus_" 12 96
& 1 Scripulum_"

_Uncia_ _Untzen_ 8 144

_Bes_ _Mark_ 1 1152

While the proportions in a _bes_ or _mark_ are the same in both scales, the actual weight values are vastly different--for instance, the _mark_ contained about 3609.6, and the _bes_ 3297 Troy Grains. Agricola also uses:

_Selibra_ _Halb-pfundt_
_Libra_ _Pfundt_
_Centumpondium_ _Centner_.

As the Roman _libra_ contains 12 _unciae_ and the German _pfundt_ 16 _untzen_, the actual weights of these latter quantities are still further apart--the former 4946 and the latter 7219 Troy grains.

[40] There are no tables in the Latin text, the whole having been written out _in extenso_, but they have now been arranged as above, as being in a much more convenient and expressive form.

[41] See note 39 above.

[42] See note 27, p. 242, for discussion of this "Assay ton" arrangement.

[43] _Agrippinenses_ and _Antuerpiani_.