Throughout the commercial history of civilised countries the digging out of riches from the bowels of the earth has for ever played an important part; and from among the minerals so obtained the currency of our world has always been minted. It is my purpose to suggest that in this there is clearly a resemblance between the civilised State and the primitive. But that which is mined by the one is sometimes vastly different from the wealth that is sought by the other. The gold of the Yukon, or the diamonds of Kimberley, are the highest ideals of civilised States; but possessions much more humble often suffice the primitive, and in the Sahara that which is sought by the indigenous tribes, and prized, as a necessity and as a currency, is humble salt of the earth. It is possible that salt has been a medium of currency in the Sahara for all time. It was the Arabs, in the past, who brought the cowrie from the north coast of Africa to introduce it into the Sahara, and the rich countries farther south, as “money” to assist them in their trade; but the silver of the white man has displaced the cowrie now, while salt, because of its tangible value, continues to be a ready medium of purchase. Therefore salt has outlived the cowrie, which, after all, had little more than an ornamental value. In a few places, renowned to-day, and doubly renowned in the legendary history of the Sahara, there exist, in the remote interior, age-old salt-pits of inexhaustible supply. They are worked to-day as of old, and the methods of centuries are unchanged. But the trade is diminishing. The tide of the white man’s advance in Africa is having an influence on distant markets; and that influence is reflected at the remote source of supply. No longer do the great native populations of the Western Sudan depend chiefly on the Sahara for their salt, for to-day whole shiploads of the commercial commodity are imported by way of the west coast to vie with the supply of the renowned salt deposits of the Sahara, that were wont to supply half a continent. But, despite the strength of the foreign invasion, there has always been a native prejudice against the imported salt and a liking for the natural salt of the Sahara—a prejudice that the importer has been fighting down ever since he entered the field—and it is no doubt that favourable prejudice, along with the existing value of salt as currency, has much to do with the continuance of a curious and primitive trade in the interior of the Sahara.