When the silver is seen to be thoroughly refined, the artificer removes the coals from the test with a shovel. Soon afterward he draws water in a copper ladle, which has a wooden handle four feet long; it has a small hole at a point half-way between the middle of the bowl and the edge, through which a hemp seed just passes. He fills this ladle three times with water, and three times it all flows out through the hole on to the silver, and slowly quenches it; if he suddenly poured much water on it, it would burst asunder and injure those standing near. The artificer has a pointed iron bar, three feet long, which has a wooden handle as many feet long, and he puts the end of this bar into the test in order to stir it. He also stirs it with a hooked iron bar, of which the hook is two digits wide and a palm deep, and the iron part of its handle is three feet long and the wooden part the same. Then he removes the test from the hearth with a shovel or a fork, and turns it over, and by this means the silver falls to the ground in the shape of half a sphere; then lifting the cake with a shovel he throws it into a tub of water, where it gives out a great sound. Or else, having lifted the cake of silver with a fork, he lays it upon the iron implement similar to tongs, which are placed across a tub full of water; afterward, when cooled, he takes it from the tub again and lays it on the block made of hard wood and beats it with a hammer, in order to break off any of the powder from the test which adheres to it. The cake is then placed on the implement similar to tongs, laid over the tub full of water, and cleaned with a bundle of brass wire dipped into the water; this operation of beating and cleansing is repeated until it is all clean. Afterward he places it on an iron grate or tripod; the tripod is a palm and two digits high, one and a half digits wide, and its span is two palms wide; then he puts burning charcoal under the tripod or grate, in order again to dry the silver that was moistened by the water. Finally, the Royal Inspector[42] in the employment of the King or Prince, or the owner, lays the silver on a block of wood, and with an engraver's chisel he cuts out two small pieces, one from the under and the other from the upper side. These are tested by fire, in order to ascertain whether the silver is thoroughly refined or not, and at what price it should be sold to the merchants. Finally he impresses upon it the seal of the King or the Prince or the owner, and, near the same, the amount of the weight.
END OF BOOK X.
FOOTNOTES:
[2] The reagents mentioned in this Book are much the same as those of Book VII, where (p. [220]) a table is given showing the Latin and Old German terms. Footnotes in explanation of our views as to these substances may be most easily consulted through the [index].
[3] Aqua valens, literally strong, potent, or powerful water. It will appear later, from the method of manufacture, that hydrochloric, nitric, and sulphuric acids and aqua regia were more or less all produced and all included in this term. We have, therefore, used either the term aqua valens or simply aqua as it occurs in the text. The terms aqua fortis and aqua regia had come into use prior to Agricola, but he does not use them; the Alchemists used various terms, often aqua dissolvia. It is apparent from the uses to which this reagent was put in separating gold and silver, from the method of clarifying it with silver and from the red fumes, that Agricola could have had practical contact only with nitric acid. It is probable that he has copied part of the recipes for the compounds to be distilled from the Alchemists and from such works as the Probierbüchlein. In any event he could not have had experience with them all, for in some cases the necessary ingredients for making nitric acid are not all present, and therefore could be of no use for gold and silver separation. The essential ingredients for the production of this acid by distillation, were saltpetre, water, and either vitriol or alum. The other substances mentioned were unnecessary, and any speculation as to the combinations which would result, forms a useful exercise in chemistry, but of little purpose here. The first recipe would no doubt produce hydrochloric acid.
[Pg 440][4] Agricola, in the Interpretatio, gives the German equivalent for the Latin aerugo as Spanschgrün—"because it was first brought to Germany from Spain; foreigners call it viride aeris (copper green)." The English "verdigris" is a corruption of vert de grice. Both verdigris and white lead were very ancient products, and they naturally find mention together among the ancient authors. The earliest description of the method of making is from the 3rd Century B.C., by Theophrastus, who says (101-2): "But these are works of art, as is also Ceruse (psimythion) to make which, lead is placed in earthen vessels over sharp vinegar, and after it has acquired some thickness of a kind of rust, which it commonly does in about ten days, they open the vessels and scrape off, as it were, a kind of foulness; they then place the lead over the vinegar again, repeating over and over again the same method of scraping it till it is wholly dissolved; what has been scraped off they then beat to powder and boil for a long time; and what at last subsides to the bottom of the vessel is the white lead.... Also in a manner somewhat resembling this, verdigris (ios) is made, for copper is placed over lees of wine (grape refuse?), and the rust which it acquires by this means is taken off for use. And it is by this means that the rust which appears is produced." (Based on Hill's translation.) Vitruvius (VII, 12), Dioscorides (V, 51), and Pliny (XXXIV, 26 and 54), all describe the method of making somewhat more elaborately.