The mineral wealth of Bolivia has been proverbial almost from time immemorial. The silver-mines of Potosi have long been celebrated as perhaps the richest deposit of silver ore in the world. From the year 1545, when they were discovered, to the year 1864, these mines, according to official data, produced the enormous sum of $2,904,902,690 of our money. Besides Potosi there are other rich silver-mines, and many large deposits of gold. The great want of these mines is skilled labor and improved modern machinery. In early days the Indians were forced to work them against their will, and were treated with great harshness and cruelty. The historical student will call to mind the efforts of philanthropists to mitigate their sufferings. When their labor could no longer be controlled, the mines fell into comparative decay. The Indians will not work them with energy and industry to-day. They doubtless hold in memory through their traditions the wrongs inflicted on their ancestors by merciless taskmasters. If worked by experienced miners, with all the improved modern machinery, the gold and silver deposits would yield as abundant returns, perhaps, as in the days of their early history. Recently a party of Californians have gone into the country and taken charge of a gold-mine. If a good many others would follow them, mining in Bolivia would experience a renaissance that would remind the Bolivians of the El Dorado of the olden time. [Illustration: A BOLIVIAN ELEVATOR.] The most useful to mankind of all the natural products of South America was quinine, the drug made from the bark of the cinchona-tree, which was discovered in Bolivia by a Franciscan friar in the early days of the Conquest, and was called cinchona in honor of the Countess of Conchona, whose husband was the Viceroy of Peru. She introduced it into Spain as a remedy for fevers, and there is no drug in the catalogue that has been used in such quantities or with such success by suffering mankind. The entire supply formerly came from Peru and Bolivia, and it was known as Peruvian bark, but afterwards the forests along the entire chain of the Andes were found to contain it, and it furnished one of the chief articles of export from South America for three centuries. The supply has been greatly diminished by the destruction of the trees, as it was the habit formerly to cut down the trunk, and strip it as well as the branches of the bark. Nowadays the forests are protected by law, and the trees are allowed to stand, a portion of the bark being stripped off each year, which nature replaces again. [Illustration: A BOLIVIAN CAVALRYMAN.]