Alvaro Alonso Barba, Arte de los metales: metallurgy written at Potosi
The first original treatise on metals written in Spanish, composed by a parish priest in the Andes and approved at Potosi in 1637 by the guild of refiners whose losses it set out to cure. It records a hot amalgamation process its author found by accident in a copper pot, his refusal to keep it secret, the monopoly he was granted and waived, and a chapter on where the quicksilver goes. It is read here in the reprint the Peruvian mining tribunal ordered in 1817, nearly two centuries later.
Why this wins its question: Barba is a name in histories of metallurgy and almost never a text anyone quotes: coverage settles for "invented pan amalgamation, published Madrid 1640, translated into English". This object opens the volume instead. It transcribes the discovery chapter in which the process is found by accident in a copper pot and an expected transmutation is explicitly disavowed; the 1637 approbation by the deputies of the Potosi guild of azogueros, which shows practitioners certifying the book against their own losses; the author's record that he was granted an exclusive licence by the Real Audiencia de La Plata and waived it for everyone; and the chapter in which the trade's own rule of thumb — at least as much quicksilver consumed as silver produced — is set down and then argued about. It is read in the Lima 1817 reprint, which is itself the evidence that the Peruvian mining tribunal still thought the book operational one hundred and eighty years on.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
The title page of the copy read here gives the work and its author in full: "ARTE DE LOS METALES, EN QUE SE ENSEÑA EL VERDADERO BENEFICIO DE LOS DE ORO Y PLATA POR AZOGUE; EL MODO DE FUNDIRLOS TODOS, Y COMO SE HAN DE REFINAR Y APARTAR UNOS DE OTROS. COMPUESTO POR EL LICENCIADO ALVARO ALONSO BARBA, natural de la villa de Lepe en la Andalucia, cura en la Imperial de Potosi de la parroquia de San Bernardo." The volume is "NUEVAMENTE AHORA AÑADIDO CON EL TRATADO DE LAS ANTIGUAS MINAS DE ESPAÑA, que escribio Don Alonso Carrillo y Laso", and its imprint reads "REIMPRESO POR EL REAL TRIBUNAL DE MINERIA DE ESTA CAPITAL DE ORDEN DEL EXCMO. SR VIREY. LIMA 1817. En la imprenta de los Huerfanos."
That imprint is itself the strongest available evidence of the book's working life. A treatise composed in the Andes in the 1630s was still being put into the hands of Peruvian miners in 1817 — not by an antiquarian press but by the Real Tribunal de Mineria of Lima, on the order of the viceroy, in the last years of the viceroyalty. The instrument of its survival was the same kind of corporate mining body that the crown had founded in New Spain a generation earlier.
The book was vetted by the men who would have to use it. The approbation printed in the volume is headed "APROBACION DE LOS DIPUTADOS DE LA villa de Potosi" and is signed by Diego de Padilla, Alferez Real and Alcalde Ordinario, with Andres de Sandoval and Bernardo de Ureña, "Diputados que somos del gremio de los azogueros de ella" — the deputies of the guild of amalgamation-mill owners. They examined it by order of the president of the Real Audiencia de La Plata, and they name the problem it addresses in their own losses: "los daños que hemos experimentado en las perdidas de Azogue, y en no haber sacado toda la ley a los metales". They sign at Potosi on 15 March 1637.
Libro Tercero opens with the discovery narrative in the author's own voice, and it is an account of an accident rather than of a programme. Residing at Tarabuco, a town of the province of los Charcas eight leagues from the city of La Plata, he wanted to test one of several ways he had read of extracting quicksilver, which had to be done in a vessel of iron; lacking one, he tried it in an ordinary small copper pot, "un perolito de los ordinarios de Cobre", and, not getting the effect he hoped, added materials, among them finely ground silver ore. He drew off in a short time a small quantity of amalgam and silver, "que al principio, como a poco experimentado, me altero no poco".
What follows is the disavowal of an alchemical hope, printed by the man who had entertained it. He was undeceived quickly, "advirtiendo que era la Plata que el metal tenia la que el Azogue habia recogido, y no otra en que se hubiese en parte trasmutado" — the silver was the silver the ore already held, gathered by the quicksilver, and not silver transmuted into being. The claim he then makes is the modest one: he was content with the new and brief mode of treating ores that he had found by chance.
He did not keep it. He improved the method over many years of continual trials, "usandolo y comunicandolo publicamente, sin hacer misterio de reservar para mi solo este, ni otros secretos", and he records that the Real Audiencia de La Plata granted him a provision that no one should use the process without his licence — a monopoly he says he waived for everyone: "sin interes ninguno lo he permitido a todos", reserving to himself only some particulars, which the following chapters then disclose.
The same chapter records a priority dispute and answers it with an unusual admission. Others, he writes, had claimed the invention and asked for advantageous rewards in different places, and had shown by their own errors that they were not the inventors. Of himself he says only that he learned it from nobody, and then concedes the limit of his own knowledge: the world being so wide in ages and regions, he does not know whether it may have been used somewhere before, only that no author ancient or modern makes any memory of it.
Libro Segundo opens on a demand for competence and public regulation rather than on technique. Its first chapter is headed "QUE EL BENEFICIO DE LOS METALES NO le use sino quien lo entienda, y con licencia y examen de la justicia" — that no one should practise the refining of ores except one who understands it, and then only with a licence and an examination by the magistrate. The argument for examined and licensed refiners is thus in print in the Andes a century before the Bourbon mining colleges.
The book carries a contemporary figure for what Potosi had yielded, and it should be read as an interested man's round number rather than as an audited account: "De quatrocientos y cincuenta millones de pesos pasan hoy los que ha dado el famoso cerro y villa Imperial de Potosi", a sum, he writes, enough to build another mountain of silver. The rhetorical flourish that follows — reales de a ocho laid edge to edge would cover sixty leagues of ground square — is offered by the author himself as a way of making the quantity imaginable.
The cost side of the technology is in the book, stated as an engineering problem. Chapter XXI of Libro Segundo is headed "Que en el lavar de los caxones se causa la falta o perdida del Azogue", and it reports the received experience of the trade in a figure: the most skilful refiner consumes "por lo menos, otro tanto Azogue como saca de Plata" — at least as much quicksilver as he takes out silver. Barba disputes the theory behind that experience, holding that the metal is not truly consumed but carried off imperceptibly with the water and the lamas in the washing. Either way the mercury leaves the works, and on his own account it leaves with the tailings.
The natural philosophy in which all this is set is pre-chemical and the book does not hide it. Libro Primero begins from metals, stones, earths and juices as "quatro generos de mixtos" and argues about the elemental earth against Aristotle and Straton of Lampsacus; Libro Tercero's second chapter is "De la antipatia y simpatia que hay entre los metales y cosas minerales"; and the ore that started the discovery was added in the hope that the "reliquias de semilla y virtud mineral" in the stones would matter. A working process was arrived at through a theory that was wrong.
The limits of this object are worth stating plainly. In the pages opened and read here — the front matter, the openings of the three books, the chapter on quicksilver losses and the table of chapters — the labour that fed Potosi is not accounted for: the treatise addresses itself to the owners of mills and to the crown's officers, and the draft rotation that supplied the Andean mines is not priced anywhere in what was read. The book is evidence about a technique and about who certified it, not about who worked it.