BOOK X.
UESTIONS as to the methods of smelting ores and
of obtaining metals I discussed in Book IX.
Following this, I should explain in what manner the
precious metals are parted from the base metals, or
on the other hand the base metals from the precious1.
Frequently two metals, occasionally more than
two, are melted out of one ore, because in
nature generally there is some amount of gold in
silver and in copper, and some silver in gold, copper,
lead, and iron ; likewise some copper in gold, silver, lead, and iron, and
some lead in silver ; and lastly, some iron in copper2. But I will begin with
gold.
Gold is parted from silver, or likewise the latter from the former, whether
it be mixed by nature or by art, by means of aqua valens3, and by powders
which consist of almost the same things as this aqua. In order to preserve the
sequence, I will first speak of the ingredients of which this aqua is made, then
of the method of making it, then of the manner in which gold is parted from
silver or silver from gold. Almost all these ingredients contain vitriol or
alum, which, by themselves, but much more when joined with saltpetre, are
powerful to part silver from gold. As to the other things that are added to
them, they cannot individually by their own strength and nature separate
those metals, but joined they are very powerful. Since there are many
combinations, I will set out a few. In the first, the use of which is common
and general, there is one libra of vitriol and as much salt, added to a third of a
libra of spring water. The second contains two librae of vitriol, one of saltpetre, and as much spring or river water by weight as will pass away whilst
the vitriol is being reduced to powder by the fire. The third consists of four
librae of vitriol, two and a half librae of saltpetre, half a libra of alum, and one
and a half librae of spring water. The fourth consists of two librae of vitriol,
as many librae of saltpetre, one quarter of a libra of alum, and three-quarters
of a libra of spring water. The fifth is composed of one libra of saltpetre,
Wile a precioso.
'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.
3Aqua 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.
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