=154. Importance of the precious metals in the American trade; effect on prices in Europe.=—The American continent offered at first only one class of wares of prime importance, namely, the precious metals. The Spanish secured great quantities of gold in the early years of their conquests, but about 1550 the output of gold was exceeded by that of silver, which reached enormous proportions, as a result of the discovery of new mines in Mexico and Peru, and by the use of the amalgamation process. Before 1550 the production of the precious metals in Europe and Africa exceeded the supply from the New World, but then the balance changed; and during the seventeenth century the American supply was more than five-fold that gained in the Old World. The result was an increase in the stock of money in Europe so great that a revolution in prices ensued; silver became so plentiful that a given weight of it would purchase only one half or one third, sometimes even one fourth or one fifth, of what it would have bought before the discovery of the American mines. The serious results of this price revolution on different classes in Europe must be left to the imagination of the reader, as they lie outside the scope of this manual. No other American product competed in importance with silver, in the early period, but as the North American continent and the West Indies were settled with whites and negroes some important staples were brought from those parts to Europe. The islands proved to be especially well suited to the production of sugar, while the mainland contributed in tobacco, a ware before unknown in Europe, but one which could soon rely on a large and increasing demand. Food staples like maize and potatoes continued unimportant, not only as wares of commerce but also as articles of European production, until comparatively recent times.