A History of Inventions, Discoveries, and Origins (Vol. 1&2). Johann Beckmann
vol. v. p. 617.
524 “A little before that period came to Rome John di Castro, with whom the Pontiff had been acquainted when he carried on trade at Basle, and was banker to Pope Eugenius. His father, Paul, was a celebrated lawyer of his time, who sat many years in the chair at Padua, and filled all Italy with his decisions; for law-suits were frequently referred to him, and judges paid great respect to his authority, as he was a man of integrity and sound learning. At his death he left considerable riches, and two sons arrived to the age of manhood, the elder of whom, following the profession of the father, acquired a very extensive knowledge of law. The other, who was a man of genius, and who applied more to study, made himself acquainted with grammar and history: but, being fond of travelling, he resided some time at Constantinople, and acquired much wealth by dyeing cloth made in Italy, which was transported thither and committed to his care, on account of the abundance of alum in that neighbourhood. Having by these means an opportunity of seeing daily the manner in which alum was made, and from what stones or earth it was extracted, he soon learned the art. When, by the will of God, that city was taken and plundered about the year 1453, by Mahomet II., emperor of the Turks, he lost his whole property; but, happy to have escaped the fire and sword of these cruel people, he returned to Italy, after the assumption of Pius II., to whom he was related, and from whom he obtained, as an indemnification for his losses, the office of commissary-general over all the revenues of the Apostolic Chamber, both within and without the city. While, in this situation, he was traversing all the hills and mountains, searching the bowels of the earth, leaving no stone or clod unexplored, he at length found some alum-stone in the neighbourhood of Tolfa. Old Tolfa is a town belonging to two brothers, subjects of the Church of Rome, and situated at a small distance from Civita Vecchia. Here there are high mountains, retiring inland from the sea, which abound with wood and water. While Castro was examining these, he observed that the grass had a new appearance. Being struck with wonder, and inquiring into the cause, he found that the mountains of Asia, which enrich the Turkish treasury by their alum, were covered with grass of the like kind. Perceiving several white stones, which seemed to be minerals, he bit some of them, and found that they had a saltish taste. This induced him to make some experiments by calcining them, and he at length obtained alum. He repaired therefore to the Pontiff, and addressing him said, ‘I announce to you a victory over the Turk. He draws yearly from the Christians above three hundred thousand pieces of gold, paid to him for the alum with which we dye wool different colours, because none is found here but a little at the island of Hiscla, formerly called Ænaria, near Puteoli, and in the cave of Vulcan at Lipari, which, being formerly exhausted by the Romans, is now almost destitute of that substance. I have however found seven hills, so abundant in it, that they would be almost sufficient to supply seven worlds. If you will send for workmen, and cause furnaces to be constructed, and the stones to be calcined, you may furnish alum to all Europe; and that gain which the Turk used to acquire by this article, being thrown into your hands, will be to him a double loss. Wood and water are both plenty, and you have in the neighbourhood the port of Civita Vecchia, where vessels bound to the West may be loaded. You can now make war against the Turk: this mineral will supply you with the sinews of war, that is money, and at the same time deprive the Turk of them.’ These words of Castro appeared to the Pontiff the ravings of a madman: he considered them as mere dreams, like the predictions of astrologers; and all the cardinals were of the same opinion. Castro, however, though his proposals were often rejected, did not abandon his project, but applied to his Holiness by various persons, in order that experiments might be made in his presence, on the stones which he had discovered. The Pontiff employed skilful people, who proved that they really contained alum; but lest some deception might have been practised, others were sent to the place where they had been found, who met with abundance of the like kind. Artists who had been employed in the Turkish mines in Asia were brought from Genoa; and these, having closely examined the nature of the place, declared it to be similar to that of the Asiatic mountains which produce alum; and, shedding tears for joy, they kneeled down three times, worshiping God, and praising his kindness in conferring so valuable a gift on our age. The stones were calcined, and produced alum more beautiful than that of Asia, and superior in quality. Some of it was sent to Venice and to Florence, and, being tried, was found to answer beyond expectation. The Genoese first purchased a quantity of it, to the amount of twenty thousand pieces of gold; and Cosmo of Medici for this article laid out afterwards seventy-five thousand. On account of this service, Pius thought Castro worthy of the highest honours and of a statue, which was erected to him in his own country, with this inscription: ‘To John di Castro, the inventor of alum;’ and he received besides a certain share of the profit. Immunities and a share also of the gain were granted to the two brothers, lords of Tolfa, in whose land the aluminous mineral had been found. This accession of wealth to the Church of Rome was made, by the divine blessing, under the pontificate of Pius II.; and if it escape, as it ought, the hands of tyrants, and be prudently managed, it may increase and afford no small assistance to the Roman Pontiffs in supporting the burdens of the Christian religion.”—Pii Secundii Comment. Rer. Memorab. quæ temp. suis contigerunt. Francof. 1614, fol. p. 185.
525 “The Frangipani a third time acquired lands in the kingdom of Naples. When they possessed in Maremma di Roma, Tolfa, Castello, and a jurisdiction which brings at present eighty thousand crowns annually to the Church, it happened that a son of Paul di Castro, a celebrated doctor, and a vassal of these lords, who had been many years a slave in Turkey to an alum-merchant, returned free to his own country; and observing that in the territories of Tolfa there was abundance of alum mineral, he gave notice of it to Lodovico Frangipani, his lord, and was the cause of greatly increasing his revenues. Pope Paul II., however, pretending that the mineral belonged to the Apostolic See, as supreme lord of the fief, and not being able to persuade Lodovico to give it up to the Church, he declared war against him, but was vigorously opposed by Lodovico and his brother Peter, lords of Tolfa, assisted by the Orsini their relations; so that the Pope was obliged to bring about an accommodation with them by means of king Ferrante I., and to pay them as the price of Tolfa sixteen thousand crowns of gold, of which Lodovico gave twelve thousand to the king, and was invested by him in the lordship of Serino in the year 1469.”
526 Ferbers Briefe über Welschland, p. 246.
527 “This year (1460) is distinguished by the discovery of alum at Tolfa vecchia, no one there having been acquainted with it till that period: and this happened by means of one John di Castro, who had acquired some knowledge of it from a young man of Corneto, and a Genoese, who had learned in Turkey the whole process of making it. The said John having observed that in the mountains of Tolfa there were undoubtedly veins of alum, he caused some of the earth and stones to be dug up, and the first experiments were made on them at Viterbo in the following manner. The stones were first calcined in a furnace; a large quantity of water was then thrown over them; and when they were entirely dissolved, the water was boiled in great leaden caldrons; after which it was poured into wooden vessels, where, evaporating by degrees, the result was alum of the most perfect kind. Pope Pius II., sensible of the great benefit which might arise from this mineral to the Apostolic Chamber, employed more than eight hundred persons at Tolfa in preparing it.”—Historia della Città de Viterbo, di Feliciano Bussi. In Roma 1742, fol. p. 262.
528 Museo di Fisica, &c. Ven. 1697, p. 152.
529 Viaggi, vii. p. 234.
530 Anno 1458. “Rock alum, which the Greeks call pharno, was at this time first discovered by a Genoese in the territories of Volterra, where being boiled and found to be good, it began to be dug up afterwards in many of the mountains of Italy. Till that period the Italians had made no use of mines of this kind; for our alum was all brought from Turkey. The above discovery was therefore a great advantage to us.”