A commentator on Aristotle, writing in the 4th century A.D., calls certain instruments used for fusion and calcination "_chuika organa_," that is, instruments for melting and pouring. Hence, probably, came the adjective _chyic_ or _chymic_, and, at a somewhat later time, the word _chemia_ as the name of that art which deals with calcinations, fusions, meltings, and the like. The writer of a treatise on astrology, in the 5th century, speaking of the influences of the stars on the dispositions of man, says: "If a man is born under Mercury he will give himself to astronomy; if Mars, he will follow the profession of arms; if Saturn, he will devote himself to the science of alchemy (_Scientia alchemiae_)." The word _alchemia_ which appears in this treatise, was formed by prefixing the Arabic _al_ (meaning _the_) to _chemia_, a word, as we have seen, of Greek origin. It is the growth, development, and transformation into chemistry, of this _alchemia_ which we have to consider. Alchemy, that is, _the_ art of melting, pouring, and transforming, must necessarily pay much attention to working with crucibles, furnaces, alembics, and other vessels wherein things are fused, distilled, calcined, and dissolved. The old drawings of alchemical operations show us men busy calcining, cohobating, distilling, dissolving, digesting, and performing other processes of like character to these. The alchemists could not be accused of laziness or aversion to work in their laboratories. Paracelsus (16th century) says of them: "They are not given to idleness, nor go in a proud habit, or plush and velvet garments, often showing their rings on their fingers, or wearing swords with silver hilts by their sides, or fine and gay gloves on their hands; but diligently follow their labours, sweating whole days and nights by their furnaces. They do not spend their time abroad for recreation, but take delight in their laboratories. They put their fingers among coals, into clay and filth, not into gold rings. They are sooty and black, like smiths and miners, and do not pride themselves upon clean and beautiful faces." In these respects the chemist of to-day faithfully follows the practice of the alchemists who were his predecessors. You can nose a chemist in a crowd by the smell of the laboratory which hangs about him; you can pick him out by the stains on his hands and clothes. He also "takes delight in his laboratory"; he does not always "pride himself on a clean and beautiful face"; he "sweats whole days and nights by his furnace."