[961] Kircher speaks of this being still the case in his time.
[962] See Chapter [19] of this Book.
[963] “Vomica liquoris æterni.” Mercury or quicksilver becomes solidified and assumes a crystalline texture at 40° below zero. It is found chiefly in the state of sulphuret, which is decomposed by distillation with iron or lime. It is also found in a native state.
[964] “Argentum vivum,” “living silver.”
[965] Ajasson thinks that this is not to be understood literally, but that Pliny’s meaning is, that mercury is a universal dissolvent.
[966] “Permanans tabe dirâ.”
[967] The specific gravity of mercury is 13.598, that of hammered gold 19.361. Platinum is only a recent discovery.
[968] “Id unum ad se trahit.”
[969] “The first use of quicksilver is commonly reckoned a Spanish invention, discovered about the middle of the sixteenth century; but it appears from Pliny, that the ancients were acquainted with amalgam and its use, not only for separating gold and silver from earthy particles, but also for gilding.”—Beckmann, Hist. Inv., Vol. I. p. 15. Bohn’s Edition.
[970] See the description of the mode of gilding, given in Chapter [20] of this Book. Beckmann has the following remarks on the present passage: “That gold-leaf was affixed to metals by means of quicksilver, with the assistance of heat, in the time of Pliny, we are told by himself in more passages than one. The metal to be gilded was prepared by salts of every kind, and rubbed with pumice-stone in order to clean it thoroughly (see Chapter 20), and to render the surface a little rough. This process is similar to that used at present for gilding with amalgam, by means of heat, especially as amalgamation was known to the ancients. But, to speak the truth, Pliny says nothing of heating the metal after the gold is applied, or of evaporating the quicksilver, but of drying the cleaned metal before the gold is laid on. Had he not mentioned quicksilver, his gilding might have been considered as that with gold leaf by means of heat, dorure en feuille à feu, in which the gold is laid upon the metal after it has been cleaned and heated, and strongly rubbed with blood-stone, or polished steel. Felibien (Principes de l’Architecture. Paris, 1676, p. 280) was undoubtedly right when he regretted that the process of the ancients, the excellence of which is proved by remains of antiquity, has been lost.”—Hist. Inv. Vol. II. pp. 294, 295. Bohn’s Edition.