Until the present century Peruvian bark was used in its crude state, and numerous attempts were made at different times to discover the actual healing principle in the bark, before success was finally attained. The first trial which is worthy of attention was made in 1779 by the chemists Buguet and Cornette, who recognised the existence of an essential salt, a resinous and an earthy matter in quinquina bark. In 1790 Fourcroy discovered the existence of a colouring matter, afterwards called _chinchona red_, and a Swedish doctor named Westring, in 1800, believed that he had discovered the active principle in quinquina bark. In 1802 the French chemist Armand Seguin undertook the bark trade on a large scale, and found it necessary to study the means of discovering good barks, and distinguishing them from bad ones. He found that the best quinquina bark was precipitated by tannin, while the bad was not precipitated by that substance. In 1803 another chemist found a crystalline substance in the bark which he called "_sel essentiel fébrifuge_" but it was nothing more than the combination of lime with an acid which was named _quinic acid_. Reuss, a Russian chemist, in 1815, was the first to give a tolerable analysis of quinquina bark; and about the same time Dr. Duncan of Edinburgh suggested that a real substance existed as a febrifugal principle. Dr. Gomez, a surgeon in the Portuguese navy, in 1816, was the first to isolate this febrifugal principle hinted at by Dr. Duncan, and he called it _chinchonine_.[28] But the final discovery of quinine is due to the French chemists Pelletier and Caventou, in 1820. They considered that a vegetable alkaloid, analogous to morphine and strychnine, existed in quinquina bark; and they afterwards discovered that the febrifugal principle was seated in two alkaloids, separate or together, in the different kinds of bark, called _quinine_ and _chinchonine_, with the same virtues, which, however, were much more powerful in quinine. It was believed that in most barks chinchonine exists in the cellular layer, and quinine in the liber, or fibrous layer; but Mr. Howard has since shown that this view is quite incorrect.[29] In 1829 Pelletier discovered a third alkaloid, which he called _aricine_, of no use in medicine, and derived from a worthless species of chinchona, growing in most of the forests of Peru, called _C. pubescens_.[30] The organic constituents of chinchona barks are-- Quina. | Kinovic acid. Chinchonia. | Chinchona red. Aricina. | A yellow colouring matter. Quinidia. | A green fatty matter. Chinchonidia. | Starch. Quinic acid. | Gum. Tannic acid. | Lignin.