Of more importance were the so-called red woods, which came partly from India and partly from the east and west coasts of Africa; and of which the most important are the sandal wood, bar wood, and cam wood. The wood of each of these trees probably contains the same coloring matter. The color is not very easy to extract, but when used with mordants of chromium, aluminium, or tin salts, it dyes wool various shades of red and reddish-brown. These colors are very fast to milling—in other words to the action of alkalies when the wool is finished in the manufacture of broadcloth; but they are not particularly fast to light, and for this reason, as well as because of their greater expense, they have been for the most part abandoned. From India, too, were introduced the well-known brown dyes known as cutch (catechu) and gambier. These come to the market in the form of dark colored pastes, formed by evaporating infusions of leaves, seed pods, nuts, and sometimes the wood of various species of acacia and areca trees. They contain large amounts of a peculiar variety of the substance known as tannin or tannic acid, which is widely distributed among many plants, and which is very useful in dyeing, as will be described later. The brown coloring matter has been isolated, and is called catechin. Both cutch and gambier will dye cotton and wool rich shades of brown, which are quite fast to light when after-treated with copper or chromium salts. =Dyes from the New World.=—The discovery of America, and the colonizing and opening to trade of South America and the West Indies, in the sixteenth and seventeenth centuries, still further enlarged the field for dyers. _Cochineal._—One of the first dyes introduced from there was cochineal, a “grain color,” similar to kermes, already described, consisting of the dried bodies of an insect known as _coccus cacti_, because it lives upon certain kind of cactus which are native to Mexico and Central America. This dyestuff was largely used for dyeing wool and silk goods, and produced fairly fast shades of crimson or of scarlet, according to the mordant employed. But it has been replaced almost entirely now by the various acid dyes, to be described later, which are cheaper, are much easier to apply, and are of equal and, in many cases, of much greater, fastness to light.