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 precious 1 . 

 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 copper 2 . 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 valens*, 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 salt- 

 petre, 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. 



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 explana- 

 tion 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 Probierbuchlein. 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 in- 

 gredients 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. 



