The alum-work which is situated about an Italian mile northwest from Tolfa, and six from Civita Vecchia, in the territories of the Church, is by some Italian historians reckoned to have been the first. However this may be, it is certain that it is the oldest carried on at present. The founder of it was John di Castro, a son of the celebrated lawyer, Paul di Castro523, who had an opportunity at Constantinople, where he traded in Italian cloths and sold dye-stuffs, of making himself acquainted with the method of boiling alum. He was there at the time when the city fell into the hands of the Turks; and after this unfortunate event, by which he lost all his property, he returned to his own country. Pursuing there his researches in natural history, he found in the neighbourhood of Tolfa a plant which he had observed growing in great abundance in the aluminous districts of Asia: from this he conjectured that the earth of his native soil might also contain the same salt; and he was confirmed in that opinion by its astringent taste. At this time he held an important office in the Apostolic Chamber; and this discovery, which seemed to promise the greatest advantages, was considered as a real victory gained over the Turks, from whom the Italians had hitherto been obliged to purchase all their alum. Pope Pius II., who was too good a financier to neglect such a beneficial discovery, caused experiments to be first made at Viterbo, by some Genoese who had formerly been employed in the alum-works in the Levant, and the success of them was equal to his expectations. The alum, which was afterwards manufactured in large quantities, was sold to the Venetians, the Florentines, and the Genoese. The Pope himself has left us a very minute history of this discovery, and of the circumstances which gave rise to it524. Some pretend that Castro was several years a slave to a Turk who traded in alum525; others affirm that he had even been obliged to labour as a slave in alum-works526; and others, that he learned the art of boiling alum from a citizen of Corneto, a town in the dominions of the Pope, and from a Genoese, both of whom had acquired their knowledge in the Levant527. But as I do not wish to ascribe a falsehood to the Pontiff, I am of opinion that the history of this discovery must have been best known to him. He has not, indeed, established the year with sufficient correctness; but we may conclude from his relation that it must have been 1460 or 1465. The former is the year given by Felician Bussi; and the latter that given in the history of the city of Civita Vecchia.
The plant which first induced John di Castro to search for alum was that evergreen, prickly shrub, the Ilex aquifolium, or holly, which in Italy is still considered as an indication that the regions where it grows abound with that salt. But though it is undoubtedly certain that the quality of the soil may be often discovered by the wild plants which it produces, it is also true that this shrub is frequently found where there is not the smallest trace of alum; and that it is not to be seen where the soil abounds with it, as has been already remarked by Boccone528 and Tozzetti529.
Among the earliest alum-works may be reckoned that which was erected at Volterra, in the district of Pisa, in 1458, by a Genoese named Antonius530. Others say that it was constructed by an architect of Sienna; but this opinion has perhaps arisen only from the work having been farmed by a citizen of Sienna, or built at his expense. On account of this alum-work an insurrection of the inhabitants of Volterra broke out in 1472; but it was at length quelled by the Florentines, who took and plundered the city531. Brutus, who wrote his History of Florence in the year 1572, says that this alum-work was carried on in his time: but this is certainly false; for Raphael di Volterra532, who died in 1521 in his native city, expressly tells us that in his time alum was no longer boiled there; and this is confirmed by Baccius533, who also lived in the sixteenth century. At present no remains of it are left; so that Tozzetti was not able to discover the place where the alum-stones were broken534.
It appears from what has been said, that the art of boiling alum in Europe was first known in Italy, but not before the year 1548. That document therefore of the year 1284, quoted by Tozzetti, and in which alum-works, alumifodinæ, are mentioned, must, as he himself thinks, be undoubtedly false535.
The great revenue which the Apostolical Chamber derived from alum, induced many to search for aluminous minerals, and works were erected wherever they were found. Several manufactories of this substance were established therefore in various parts, which are mentioned by Baccius536, Biringoccio, and other writers of the sixteenth century. The pope however understood his own interest so well, that he never rested until he had caused all the works erected in the territories of others to be given up, and until he alone remained master of the prize. He then endeavoured by every method possible to prevent foreigners from acquiring an accurate knowledge of the art of boiling alum; and at the same time found means, by entering into commercial treaties with other nations, and by employing the medium of religion, which has always the greatest effect on weak minds, to extend his commerce in this article more and more. The price was raised from time to time, and it at length became so high that foreigners could purchase this salt at a cheaper rate from the Spaniards, and even when they sent for it to Turkey. His Holiness, that he might convert this freedom of trade into a sin, and prevent it by the terror of excommunication, artfully gave out that he meant to set apart the income arising from his alum-works to the defence of Christianity; that is, towards carrying on war against the Turks. Prohibitions and threats now followed in case any one should be so unchristian as to purchase alum from the Infidels; but every person was at liberty to make what bargain he could with his Holiness for this commodity.
In the year 1468 Pope Paul II. entered into a commercial treaty respecting alum with Charles the Bold, duke of Burgundy; but in 1504 Roman alum had risen to such an exorbitant price, that Philip the Fair, archduke of Austria, caused a council of inquiry to be held at Bruges, by which it appeared that this article could be purchased at a much cheaper rate in Turkey. Commissions therefore were sent thither for that purpose; but scarcely was this known at Rome, when a prohibition, under pain of excommunication, was issued by Pope Julius II. This pontiff however was not the only one from whom such prohibitions proceeded: bulls of the like kind were issued also by Julius III., Paul III., Paul IV., Gregory XIII. and others537.
But these means, like all those founded on the simplicity of others, could not be of long duration; and as soon as men became a little more enlightened, they learned to know their own interest, and to discover the selfishness of the Pope’s bulls. Unless Biringoccio, who visited a part of the German mines, be under a mistake, the first European alum-work out of Italy was erected in Spain; and is that still carried on with considerable profit at Almacaron, not far from Carthagena538. In the beginning of the sixteenth century very large quantities of alum were brought to Antwerp, as we learn from Guicciardini’s Description of the Netherlands.
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