Note 15 — BOOK II.

This reference should be to the De Natura Fossilium (p. 230), although there is a short reference to the matter in De Ortu et Causis (p. 59). Agricola maintained that not only were jet and amber varieties of bitumen, but also coal and camphor and obsidian. As jet (gagates) is but a compact variety of coal, the ancient knowledge of this substance has more interest than would otherwise attach to the gem, especially as some materials described in this connection were no doubt coal. The Greeks often refer to a series of substances which burned, contained earth, and which no doubt comprised coal. Such substances are mentioned by Aristotle (De Mirabilibus. 33, 41, 125), Nicander (Theriaca. 37), and others, previous to the 2nd Century B.C., but the most ample description is that of Theophrastus (23-28): "Some of the more brittle stones there also are, which become as it were burning coals when put into a fire, and continue so a long time; of this kind are those about Bena, found in mines and washed down by the torrents, for they will take fire on burning coals being thrown on them, and will continue burning as long as anyone blows them; afterward they will deaden, and may after that be made to burn again. They are therefore of long continuance, but their smell is troublesome and disagreeable. That also which is called the spinus, is found in mines. This stone, cut in pieces and thrown together in a heap, exposed to the sun, burns; and that the more, if it be moistened or sprinkled with water (a pyritiferous shale?). But the Lipara stone empties itself, as it were, in burning, and becomes like the pumice, changing at once both its colour and density; for before burning it is black, smooth, and compact. This stone is found in the Pumices, separately in different places, as it were, in [Pg 35]cells, nowhere continuous to the matter of them. It is said that in Melos the pumice is produced in this manner in some other stone, as this is on the contrary in it; but the stone which the pumice is found in is not at all like the Lipara stone which is found in it. Certain stones there are about Tetras, in Sicily, which is over against Lipara, which empty themselves in the same manner in the fire. And in the promontory called Erineas, there is a great quantity of stone like that found about Bena, which, when burnt, emits a bituminous smell, and leaves a matter resembling calcined earth. Those fossil substances that are called coals, and are broken for use, are earthy; they kindle, however, and burn like wood coals. These are found in Liguria, where there also is amber, and in Elis, on the way to Olympia over the mountains. These are used by smiths." (Based on Hill's Trans.). Dioscorides and Pliny add nothing of value to this description.

Agricola (De Nat. Fos., p. 229-230) not only gives various localities of jet, but also records its relation to coal. As to the latter, he describes several occurrences, and describes the deposits as vena dilatata. Coal had come into considerable use all over Europe, particularly in England, long before Agricola's time; the oft-mentioned charter to mine sea-coal given to the Monks of Newbottle Abbey, near Preston, was dated 1210.

Amber was known to the Greeks by the name electrum, but whether the alloy of the same name took its name from the colour of amber or vice versa is uncertain. The gum is supposed to be referred to by Homer (Od. XV. 460), and Thales of Miletus (640-546 B.C.) is supposed to have first described its power of attraction. It is mentioned by many other Greek authors, Æschylus, Euripides, Aristotle, and others. The latter (De Mirabilibus, 81) records of the amber islands in the Adriatic, that the inhabitants tell the story that on these islands amber falls from poplar trees. "This, they say, resembles gum and hardens like stone, the story of the poets being that after Phaeton was struck by lightning his sisters turned to poplar trees and shed tears of amber." Theophrastus (53) says: "Amber is also a stone; it is dug out of the earth in Liguria and has, like the before-mentioned (lodestone), a power of attraction." Pliny (XXXVII., 11) gives a long account of both the substance, literature, and mythology on the subject. His view of its origin was: "Certainly amber is obtained from the islands of the Northern Ocean, and is called by the Germans glaesum. For this reason the Romans, when Germanicus Cæsar commanded in those parts, called one of them Glaesaria, which was known to the barbarians as Austeravia. Amber originates from gum discharged by a kind of pine tree, like gum from cherry and resin from the ordinary pine. It is liquid at first, and issues abundantly and hardens in time by cold, or by the sea when the rising tides carry off the fragments from the shores of those islands. Certainly it is thrown on the coasts, and is so light that it appears to roll in the water. Our forefathers believed that it was the juice of a tree, for they called it succinum. And that it belongs to a kind of pine tree is proved by the odour of the pine tree which it gives when rubbed, and that it burns when ignited like a pitch pine torch." The term amber is of Arabic origin—from Ambar—and this term was adopted by the Greeks after the Christian era. Agricola uses the Latin term succinum and (De Nat. Fos., p. 231-5) disputes the origin from tree gum, and contends for submarine bitumen springs.