Cinchona is the bark of several species of cinchona, which grow in South America; of this bark there are several varieties, the red, the yellow, and the pale. The red is in large easily pulverized pieces, which furnish a reddish brown powder, having a bitter astringent taste. The yellow Peruvian bark was first brought to this country about the year 1790, and it resembles pretty closely in composition the red species. The pale cinchona is that generally employed in medical practice as a tonic and febrifuge.