[2838] As Fée says, these earths vary according to the nature of the soils that are brought down by the streams; in general, however, they are extremely prolific.
[2839] Fée says that Pliny is here guilty of some degree of exaggeration. See B. iii. c. 9, p. 195 of Vol. 1: also B. xviii. c. 29.
[2840] “Tophus;” formed of volcanic scoriæ. Fée remarks, that it is somewhat similar in nature to marl, and that though unproductive by itself, it is beneficial when mixed with vegetable earth. Tufa and marl appear to have been often confounded by the ancient writers.
[2841] Georg. ii. 189.
[2842] The Pteris aquilina of the modern botanists.
[2843] Marine salt, or sub-hydrochlorate of soda, Fée thinks, is here alluded to. It is still used with varied success in some parts of the west of France.
[2844] Hardouin says, that he here alludes to the proverbial saying among the ancients, “Perflare altissima ventos”—“The winds blow only on the most elevated ground.”
[2845] In B. xiv. cc. [4] and [12].
[2846] “Emisso.” Fée would appear to think that the lake suddenly made its appearance, after an earthquake, and from the context he would appear to be right. These accounts are all of them borrowed from Theophrastus.
[2847] See B. v. c. 36.