The discussion of detailed features of the process has been reserved to notes attached to the actual text, to which the reader is referred. As to the general result of liquation, Karsten (see [below]) estimates the losses in the liquation of the equivalent of 100 lbs. of argentiferous copper to amount to 32-35 lbs. of lead and 5 to 6 lbs. of copper. Percy (see [below]) quotes results at Lautenthal in the Upper Harz for the years 1857-60, showing losses of 25% of the silver, 9.1% of the copper, and 36.37 lbs. of lead to the 100 lbs. of copper, or say, 16% of the lead; and a cost of £8 6s. per ton of copper. The theoretical considerations involved in liquation have not been satisfactorily determined. Those who may wish to pursue the subject will find repeated descriptions and much discussion in the following works, which have been freely consulted in the notes which follow upon particular features of the process. It may be mentioned that Agricola's treatment of the subject is more able than any down to the 18th century. Ercker (Beschreibung Allerfürnemsten Mineralischen, etc., Prague, 1574). Lohneys (Bericht vom Bergwercken, etc., Zellerfeldt, 1617). Schlüter (Gründlicher Unterricht [Pg 492]von Hütte-Werken, Braunschweig, 1738). Karsten (System der Metallurgie V. and Archiv für Bergbau und Hüttenwesen, 1st series, 1825). Berthier (Annales des Mines, 1825, II.). Percy (Metallurgy of Silver and Gold, London, 1880).
Nomenclature.—This process held a very prominent position in German metallurgy for over four centuries, and came to have a well-defined nomenclature of its own, which has never found complete equivalents in English, our metallurgical writers to the present day adopting more or less of the German terms. Agricola apparently found no little difficulty in adapting Latin words to his purpose, but stubbornly adhered to his practice of using no German at the expense of long explanatory clauses. The following table, prepared for convenience in translation, is reproduced. The German terms are spelled after the manner used in most English metallurgies, some of them appear in Agricola's Glossary to De Re Metallica.
| English. | Latin. | German. |
| Blast furnace | Prima fornax | Schmeltzofen |
| Liquation furnace | Fornax in qua argentum et plumbum ab aere secernuntur | Saigernofen |
| Drying furnace | Fornax in qua aerei panes fathiscentes torrentur | Darrofen |
| Refining hearth | Fornax in qua panes aerei torrefacti coquuntur | Gaarherd |
| Cupellation furnace | Secunda fornax, or fornax in qua plumbum ab argento separatur | Treibherd |
| Leading | Mistura | Frischen |
| Liquating | Stillare, or distillare | Saigern |
| "Drying" | Torrere | Darren |
| Refining | Aes ex panibus torrefactis conficere | Gaarmachen |
| Liquation cakes | Panes ex aere ac plumbo misti | Saigerstock |
| Exhausted liquation cakes | Panes fathiscentes | Kiehnstock, or Kinstocke |
| "Dried" cakes | Panes torrefacti | Darrlinge |
| Slags: | ||
| from leading | Recrementa (with explanatory phrases) | Frischschlacke |
| " drying | " " " | Darrost |
| " refining | " " " | Gaarschlacke |
| Liquation thorns | Spinae (with explanatory phrases) | Saigerdörner, or Röstdörner |
| Thorns from "drying" | " " " | Darrsöhle |
| " " cupellation | " " " | Abstrich |
| Silver-lead or liquated silver-lead | Stannum | Saigerwerk or saigerblei |
| Ash-coloured copper | Aes cinereum | Pickschiefer or schifer |
| Furnace accretions or "accretions" | Cadmiae | Offenbrüche |
[Pg 494] Historical Note.—So far as we are aware, this is the first complete discussion of this process, although it is briefly mentioned by one writer before Agricola—that is, by Biringuccio (III, 5, 8), who wrote ten years before this work was sent to the printer. His account is very incomplete, for he describes only the bare liquation, and states that the copper is re-melted with lead and re-liquated until the silver is sufficiently abstracted. He neither mentions "drying" nor any of the bye-products. In his directions the silver-lead alloy was cupelled and the copper ultimately refined, obviously by oxidation and poling, although he omits the pole. In A.D. 1150 Theophilus (p. 305, Hendrie's Trans.) describes melting lead out of copper ore, which would be a form of liquation so far as separation of these two metals is concerned, but obviously not a process for separating silver from copper. This passage is quoted in the note on copper smelting (Note on p. [405]). A process of such well-developed and complicated a character must have come from a period long before Agricola; but further than such a surmise, there appears little to be recorded. Liquation has been during the last fifty years displaced by other methods, because it was not only tedious and expensive, but the losses of metal were considerable.
[2] Paries,—"Partition" or "wall." The author uses this term throughout in distinction to murus, usually applying the latter to the walls of the building and the former to furnace walls, chimney walls, etc. In order to gain clarity, we have introduced the term "hood" in distinction to "chimney," and so far as possible refer to the paries of these constructions and furnaces as "side of the furnace," "side of the hood," etc.
[Pg 495][4] From this point on, the construction of the roofs, in the absence of illustration, is hopeless of intelligent translation. The constant repetition of "tignum," "tigillum," "trabs," for at least fifteen different construction members becomes most hopelessly involved, especially as the author attempts to distinguish between them in a sort of "House-that-Jack-built" arrangement of explanatory clauses.
[Pg 496][5] In the original text this is given as the "fifth," a manifest impossibility.
[7] If Roman weights, this would be 5.6 short tons, and 7.5 tons if German centner is meant.
[Pg 501][8] This is, no doubt, a reference to Pliny's statement (XXXIII, 35) regarding litharge at Puteoli. This passage from Pliny is given in the footnote on p. [466]. Puteoli was situated on the Bay of Naples.