Arabia is the most westerly of the three peninsulas of southern Asia, a position remarkably favorable to political influence and commercial enterprise. The Mohammedans were an energetic and intelligent people, whose ancestors led a nomadic life for more than a thousand years; but from the middle of the ninth century they rose rapidly in the appreciation and extension of ennobling science. The same race who, two centuries before, had fearfully ravaged the great conservatory of learning at Alexandria, themselves became the most ardent admirers of the muses, and were unequaled proficients in the very studies they had previously, in their bigoted fury, so nearly annihilated. They garnered Greek manuscripts with the greatest assiduity, and became sufficiently masters of their import, to set a proper estimate on these valuable relics of ancient knowledge. To the Arabian mathematicians, we are indebted for most valuable improvements in arithmetic, if not in fact for its invention. They also transmitted to Europe the knowledge of algebra; and rendered still more important service to geometrical science, by preserving many works of the ancients, which, but for them, had been inevitably lost. The elements of Euclid, with other valuable treatises, were all transmitted to posterity by their means. The Arabian mathematicians of the middle ages were the first to apply to trigonometry the method of calculation which is now generally adopted. Astronomy, optics, and mechanics were cultivated with no less success; and to the Arabs especially must be accredited the origin of chemistry, that science which has been productive of so many invaluable results. This gave them a better acquaintance with nature than the Greeks or the Romans ever possessed, and was applied by them most usefully to all the necessary arts of life. "Alchemy" is an Arabic term, denoting a knowledge of the substance or composition of a thing. The transmutation of common metals into gold and silver, and the discovery of a universal medicine, were futile pursuits; but they led to the method of preparing alcohol, aqua-fortis, volatile alkali, vitriolic acid, and many other chemical compounds, which might have remained much longer unknown but for the persevering labors and patient experiments of the mediæval alchemists.