lib. xv. c. 1.
503 The halotrichum of Scopoli. The first person who discovered this salt to be vitriolic was Henkel, who calls it Atlas-vitriol. [The mineral halotrichite is, in a chemical sense, a true alum in which the sulphate of potash is replaced by the sulphate of the protoxide of iron. It is composed of one atom of protosulphate of iron, one atom of sulphate of alumina, and contains, like all the true alums, twenty-four atoms of water.]
504 Wecker De Secretis, lib. ix. 18, p. 445.
505 One instance of its being used for this purpose is found in Ammianus Marcellinus, lib. xx. c. 12.
506 [This cannot be correct; for Geber, who is supposed to have lived in the eighth century, was acquainted with three kinds of it, and describes the method of preparing burnt alum.]
507 Joh. Serapionis Arabis de simplicibus medicinis opus, cap. 410.
508 Reisebeschreibung, ii. p. 408, 409.
509 This singular appellation occurs in Valentini Historia Simplicium, and several other works.
510 Jul. Cæs. Scaligeri Exot. exercitat. Franc. 1612, 8vo, p. 325.
511 I shall here take occasion to remark, that schist seems to have been employed for making alum in the time of Agricola, as appears by his book De Ortu et Causis Subterraneorum, p. 47.
512 Mercati, Metallotheca, p. 54.
513 Pyrotechnia. Ven. 1559, 4to.
514 Leibnitii Protogæa, p. 47.
515 Bellonii Observationes, cap. lxi.
516 “In Phocis, which lies close to Ionia, there is a mountain abundant in aluminous mineral. The stones found on the top of this mountain are first calcined in the fire, and then reduced to powder by being thrown into water. The water mixed with that powder is put into a kettle; and a little more water being added to it, and the whole having been made to boil, the powder is lixiviated, and the thick part which falls to the bottom in a cake is preserved; what is hard and earthy is thrown away as of no use. The cake is afterwards suffered to dissolve in vessels for four days; at the end of which the alum is found in crystals around their edges, and the bottoms of them also are covered with pieces and fragments of the like nature. The remaining liquor, which at the end of four days does not harden, is poured into a kettle, more water and more powder are added to it, and being boiled as before, it is put into proper vessels, and the alum obtained in this manner is preserved as an article very necessary for dyers. All masters of ships bound from the Levant to Europe, consider alum as a very convenient and useful lading for vessels. … In the reign of Michael Palæologus, the first emperor of his family, some Italians requested a lease of that mountain, for which they promised to pay a certain sum annually. … The Romans and the Latins built Phocæa Nova on the sea-shore, at the bottom of that mountain which lies on the east side of it. On the west it has the island of Lesbos, on the north the neighbouring bay of Elæa, and on the south it looks towards the Ionian sea.”—Ducæ Historia Byzantina. Venet. 1729, p. 71.
517 The alum of Smyrna is mentioned by Baumé in his Experimental Chemistry, i. p. 458.
518 Some account of other Eastern alum-works is contained in a treatise of F. B. Pegolotti, written in the middle of the fourteenth century, on the state of commerce at that time, and printed in a book entitled Della decima e di varie altre gravezze imposte dal commune di Firenze. Lisbona e Lucca, 1765, 4to, 4 vols. It appears from this work, that in the fourteenth century the Italians were acquainted with no other than Turkish alum.
519 “I shall embrace this opportunity of giving a brief account of the situation of the island, and of the nature of its soil. That Ænaria has been at some time violently separated from the continent by an earthquake, seems proved by a variety of circumstances, such as calcined rocks; the ground full of caverns; and the earth, which, like that of the main land, being abundant in warm springs, and dry, feeds internal fire, and on that account contains a great deal of alum. A few years ago Bartholomew Perdix, a Genoese merchant passing this island in his way to Naples, observed some aluminous rocks scattered here and there along the sea-coast. About a hundred and sixty-three years before that period, the earth having suddenly burst by the effects of fire confined in its bowels, a considerable part of Ænaria was involved in flames. By this eruption a small town was burned and afterwards swallowed up; and large masses of rock mixed with flames, sand and smoke, thrown up where the shore looks towards Cumæ, fell upon the neighbouring fields, and destroyed the most fruitful and the most pleasant part of the island. Some of these huge pieces of rock being at that time still lying on the shore, Bartholomew, by calcining them in a furnace, extracted alum from them, and revived that art which he had brought from Rocca in Syria, where he had traded for several years, and which had been neglected in Italy for many centuries.”—Pontani Hist. Neapol. in Grævii Thesaurus Antiq. Italiæ, ix. part 3. p. 88.
520 “I must not omit to mention that about this time Bartholomew Pernix, a citizen and merchant of Genoa, who had resided long in Syria for the purpose of commerce, returned to his native country. Soon after, he made a voyage to the island of Ænaria, situated in the Tuscan sea, called formerly Pythacusa, and now in the vulgar Greek Iscla or Ischia; and being a man of an acute genius, and a diligent investigator of natural objects, he observed near the sea-coast several rocks fit for making alum. He took some fragments of them therefore, and having calcined them in a furnace, he procured from them most excellent alum. He was the first person who, to the incredible benefit of many, brought as it were again into use that art long abandoned and almost lost in Italy and the greater part of other countries. On that account his name deserves to be rescued from oblivion.”—Genuensis Rerum Annal. auct. P. Bizaro Sentinati. Antv. 1579, fol. p. 302.
521 “About that period (1459) Bartholomew Pernix, a Genoese merchant, sailing past the island of Ænaria or Ischia, learned that there were near the shore many aluminous rocks, that is to say, fit for making alum. He took some of them, therefore, and having caused them to be calcined in a furnace, he procured from them most excellent alum. This Bartholomew brought back to Italy from the city of Rocca, in Syria, where he had traded many years, the art of making alum, which had been neglected and lost for a long space of time.”—Annali della Republica di Genoa, per Agostino Giustiniano. Genoa, 1537, fol. lib. v. p. 214.
522 Dom. Bottone, Pyrologia Topographica. Neapoli, 1692, 4to. This author calls the inventor Perdix, and not Pernix.
523 Fabricii