[3121] See B. xii. c. 49, and B. xxiv. c. 28, for an account of gum resin ammoniac, a produce of the same locality. The substance here spoken of is considered by Beckmann to be nothing but common salt in an impure state. See his Hist. Inv. Vol. II. pp. 398-9, where this passage is discussed at considerable length. Ajasson, on the other hand, considers it to be Hydrochlorate of ammonia, the Sal ammoniac of commerce. According to some accounts, it was originally made in the vicinity of the Temple of Jupiter Hammon, by burning camels’ dung.
[3122] Called ἄμμος, in Greek.
[3123] See B. xxxv. c. 52.
[3124] Sal ammoniac crystallizes in octahedrons.
[3125] “Intra specus suos.” On this passage, Beckmann says, “From what is said by Pliny it may with certainty be concluded that this salt was dug up from pits or mines in Africa.—Many kinds of rock-salt, taken from the mines of Wieliczka, experience the same change in the air; so that blocks which a labourer can easily carry in the mine, can scarcely be lifted by him after being for some time exposed to the air. The cause here is undoubtedly the same as that which makes many kinds of artificial salt to become moist and to acquire more weight.”—Vol. II. p. 399, Bohn’s Ed.
[3126] According to modern notions, his reason is anything but evident.
[3127] In Celtiberia. He alludes to the mountain of salt at Cardona, near Montserrat in Catalonia.
[3128] Speaking generally, this is true; but soils which contain it in small quantities are fruitful.
[3129] A similar method is still employed, Ajasson says, at the salt-mines near Innspruck in the Tyrol.
[3130] Native bitumen; always to be found in greater or less quantities, in saliferous earths.