It will be seen that it possesses neither chloride of manganese nor chloride of aluminium, no nitrates, and no iodines; that it is, therefore, not _sea water_, properly so called, but a mineral water _sui generis_. The enormous proportion of saline matter accounts for its exceptional density, and justifies the assertion of travellers that a man floats upon its surface like a log of wood; though we can hardly credit the statement of Pococke that it is impossible to sink to the bottom. Its gravity undoubtedly endows it with extraordinary buoyancy, and to dive to any considerable depth is a matter of difficulty; but in the Dead Sea, as in other seas, man must employ his strength and skill to keep his body afloat. CHAPTER II. ARABIA DESERTA AND ARABIA PETRÆA. The traveller who starts from the southern extremity of the Dead Sea encounters a succession of deserts. To the east extend wide plains, covered with ruins, where upwards of thirty cities are to be traced in their decay, like Palmyra, by the trunks of shattered columns and the wrecks of desecrated temples. This is the once flourishing country of the Nabatheans, now haunted by some tribes of Idumean Arabs. One might not inappropriately call it the vestibule of Arabia Deserta; a name applicable to all the central and southern districts--that is to say, to nearly three-fourths of the Arabian peninsula. There the sea of sand reveals itself in all its nakedness, in all its horrors; with its implacable sky and fiery atmosphere, its sandy billows, its masses of salt, and, in certain places, with its hidden quicksands capable of devouring entire armies. The Desert of Akhaf, situated towards the extremity of the peninsula, conceals, it is said, several of these abysses, where the hapless traveller, if he set his foot upon them, would be instantly swallowed up. Thus even the Arabs regard it with an unconquerable dread. It owes its name to a Saffite king who would fain have traversed it with his troops, and who saw them perish therein even to the last man. The tradition does not inform us how he himself escaped this immense disaster. [Illustration: CARAVAN IN THE DESERT.] A European traveller, Baron de Wrede, undertook nevertheless, some twenty-five years ago, to penetrate into this soul-appalling desert, and attempted to measure the extent and depth of one of these abysses. Starting in the morning from Saba, under the guidance of a few Bedouins, he reached, after six hours' marching, the threshold of the desert of Akhaf.