[37] “In one village they only found one earthen pot containing food, which Bruce took possession of, leaving in its place a wedge of salt, which, strange to say, is still used as small money in Gondar and all over Abyssinia.”—Bruce’s “Travels in Abyssinia.”
[38] Polymnia, book vii. chap. xxx.
[39] The geographical features of this almost unknown country are peculiarly interesting, and are unique when compared with others; the great height of its mountains, its remarkable elevation, the large rivers which take their rise here, and the numerous salt lakes, the altitude of some being from 13,800 to 15,400 feet above the level of the sea, all combine to excite our curiosity, which is increased by the fact that we know next to nothing of the interior or of the habits of the people.
[40] “Many springs in Sicily contain muriate of soda; and the ‘fuime salso’ in particular is impregnated with so large a quantity that cattle refuse to drink it. There is a hot spring at St. Nectaire, in Auvergne, which may be mentioned as one of many, containing a large proportion of muriate of soda, together with magnesia and other ingredients.”—Sir Charles Lyell’s “Principles of Geology.”
[41] The Jurassic formation presents a remarkable contrast with that of the Triassic, in the profusion of organic remains; for while the latter contains next to none, the former teems with marine fossils, a proof that the strata were unfavourable for the preservation of organic structures.—Dr. Mantell’s “Wonders of Geology.”
[42] There is a mountain composed entirely of rock-salt not far from this old Moorish city; it is 500 feet in height and three miles in circumference; it is completely isolated, and gypsum is also present. In other countries there are similar enormous masses, which require to be dug out and pulverised by machinery on account of their hardness.
[43] Gypsum, or sulphate of lime, consists of sulphuric acid 46·31, lime 32·90, and water 20·79. The massive gypsum is called Alabaster; the transparent gypsum Selenite; powdered calcined gypsum forms Plaster of Paris. The fibrous gypsum has a silken lustre, and is used for ear-rings, brooches, and other ornaments. Fibrous gypsum of great beauty occurs in Derbyshire; veins and masses of this substance abound in the red marls bordering the valley of the Trent.
[44] Geological Journal, vol. iii. p. 257.
[45] Pereira’s “Materia Medica,” vol. i. p. 581.
[46] Sir Charles Lyell’s “Principles of Geology.”