[9] Three librae of silver per centumpondium would be equal to 875 ounces per short ton.
[10] As stated in note on p. [2], Agricola divided "stones so called" into four kinds; the first, common stones in which he included lodestone and jasper or bloodstone; the second embraced gems; the third were decorative stones, such as marble, porphyry, etc.; the fourth were rocks, such as sandstone and limestone.
Lodestone. (Magnes; Interpretatio gives Siegelstein oder magnet). The lodestone was well-known to the Ancients under various names—magnes, magnetis, heraclion, and sideritis. A review of the ancient opinions as to its miraculous properties would require more space than can be afforded. It is mentioned by many Greek writers, including Hippocrates (460-372 B.C.) and Aristotle; while Theophrastus (53), Dioscorides (V, 105), and Pliny (XXXIV, 42, XXXVI, 25) describe it at length. The Ancients also maintained the existence of a stone, theamedes, having repellant properties, and the two were supposed to exist at times in the same stone.
Emery. (Smiris; Interpretatio gives smirgel). Agricola (De Natura Fossilium, p. 265) says: "The ring-makers polish and clean their hard gems with smiris. The glaziers use it to cut their glass into sheets. It is found in the silver mines of Annaberg in Meissen and elsewhere." Stones used for polishing gems are noted by the ancient authors, and Dana (Syst. of Mineralogy, p. 211) considers the stone of Armenia, of Theophrastus (77), to be emery, although it could quite well be any hard stone, such as Novaculite—which is found in Armenia. Dioscorides (V, 166) describes a stone with which the engravers polish gems.
Lapis Judaicus. (Interpretatio gives Jüden stein). This was undoubtedly a fossil, possibly a pentremites. Agricola (De Natura Fossilium, p. 256) says: "It is shaped like an acorn, from the obtuse end to the point proceed raised lines, all equidistant, etc." Many fossils were included among the semi-precious stones by the Ancients. Pliny (XXXVII, 55, 66, 73) describes many such stones, among them the balanites, phoenicitis and the pyren, which resemble the above.
Trochitis. (Interpretatio gives spangen oder rederstein). This was also a fossil, probably crinoid stems. Agricola (De Natura Fossilium, p. 256) describes it: "Trochites is so called from a wheel, and is related to lapis judaicus. Nature has indeed given it the shape of a drum (tympanum). The round part is smooth, but on both ends as it were there is a module from which on all sides there extend radii to the outer edge, which corresponds with the radii. These radii are so much raised that it is fluted. The size of these trochites varies greatly, for the smallest is so little that the largest is ten times as big, and the largest are a digit in length by a third of a digit in thickness ... when immersed in vinegar they make bubbles."
[11] The "extraordinary earths" of Agricola were such substances as ochres, tripoli, fullers earth, potters' clay, clay used for medicinal purposes, etc., etc.
[Pg 117][12] Presumably the ore-body dips into a neighbouring property.
[Pg 118][13] The various kinds of iron tools are described in great detail in [Book VI].
[14] Fire-setting as an aid to breaking rock is of very ancient origin, and moreover it persisted in certain German and Norwegian mines down to the end of the 19th century—270 years after the first application of explosives to mining. The first specific reference to fire-setting in mining is by Agatharchides (2nd century B.C.) whose works are not extant, but who is quoted by both Diodorus Siculus and Photius, for which statement see [note 8, p. 279]. Pliny (XXXIII, 21) says: "Occasionally a kind of silex is met with, which must be broken with fire and vinegar, or as the tunnels are filled with suffocating fumes and smoke, [Pg 119]they frequently use bruising machines, carrying 150 librae of iron." This combination of fire and vinegar he again refers to (XXIII, 27), where he dilates in the same sentence on the usefulness of vinegar for breaking rock and for salad dressing. This myth about breaking rocks with fire and vinegar is of more than usual interest, and its origin seems to be in the legend that Hannibal thus broke through the Alps. Livy (59 B.C., 17 A.D.) seems to be the first to produce this myth in writing; and, in any event, by Pliny's time (23-79 A.D.) it had become an established method—in literature. Livy (XXI, 37) says, in connection with Hannibal's crossing of the Alps: "They set fire to it (the timber) when a wind had arisen suitable to excite the fire, then when the rock was hot it was crumbled by pouring on vinegar (infuso aceto). In this manner the cliff heated by the fire was broken by iron tools, and the declivities eased by turnings, so that not only the beasts of burden but also the elephants could be led down." Hannibal crossed the Alps in 218 B.C. and Livy's account was written 200 years later, by which time Hannibal's memory among the Romans was generally surrounded by Herculean fables. Be this as it may, by Pliny's time the vinegar was generally accepted, and has been ceaselessly debated ever since. Nor has the myth ceased to grow, despite the remarks of Gibbon, Lavalette, and others. A recent historian (Hennebert, Histoire d' Annibal II, p. 253) of that famous engineer and soldier, soberly sets out to prove that inasmuch as literal acceptance of ordinary vinegar is impossible, the Phoenicians must have possessed some mysterious high explosive. A still more recent biographer swallows this argument in toto. (Morris, "Hannibal," London, 1903, p. 103). A study of the commentators of this passage, although it would fill a volume with sterile words, would disclose one generalization: That the real scholars have passed over the passage with the comment that it is either a corruption or an old woman's tale, but that hosts of soldiers who set about the biography of famous generals and campaigns, almost to a man take the passage seriously, and seriously explain it by way of the rock being limestone, or snow, or by the use of explosives, or other foolishness. It has been proposed, although there are grammatical objections, that the text is slightly corrupt and read infosso acuto, instead of infuso aceto, in which case all becomes easy from a mining point of view. If so, however, it must be assumed that the corruption occurred during the 20 years between Livy and Pliny.