CHEMISTRY, the science which deals with the composition and transformations of matter, had its origin in remote antiquity. In its earliest form it was purely empirical, a mass of disconnected facts which were brought to light in the natural course of development of various industries. In the extraction of metals from their ores, in the preparation of drugs and medi cines, in the processes of dyeing and the like, many chemical data were discovered; and of such facts a large number were known to the ancient Egyptians. Indeed, one plausible deriva tion of the word *chemistry* is from Khetn, an early name for Egypt, which has reference to the blackness of its soil. With this name the Arabic word chema, to hide, seems to have some relation; and when we remember that much ancient learning was for us by Arabian scholars, the descriptions of chemistry as the Egyptian science, or as the hidden or occult art, become intelligible. Secrecy was a characteristic of its early practitioners.
The one fundamental fact of chemistry is, that matter can undergo apparent transforma tions of kind, one substance being converted into another. For instance, wood becomes charcoal, and iron is changed to rust; and facts like these were evident even to the most primitive observers. As philosophy developed, these data were necessarily considered, the nature of matter was discussed and attempts were made to correlate and explain the phe nomena. Much of the early speculation was vague and mystical, and has little significance to-day; but a part of it was intensely practiceand gave a definite purpose to investigation. I matter can be transformed from one substance to another, why should not the possibility of change be universal? All metals, it was seen, had certain properties in common, and so trans mutability between them was almost taken for granted. Thus alchemy arose, with its search for the philosopher's stone and its attempts to convert base metals into gold; and from alchemy the chemistry of to-day is lineally descended. The discoveries, even the failures, of the alchemists laid the foundations of our modern science, and pointed out the best paths for investigation to follow.
The Greek philosophers, and especially Aris totle, in their attempts to interpret matter, as sumed existence of four elements, namely, earth, water, air and fire. These names, how ever denoted properties rather than things, and implied the attributes of coldness, wetness, dry ness and heat. The properties of matter were determined by these conditions, and could he expressed by the varying degrees under which the latter were displayed. Of chemical com bination, as we understand it, the ancients seem to have had no clear conception; they sought to solve the problems of the universe by reasoning alone; the experimental method as a test of truth had not become a court of last appeal, To the alchemists, on the other hand, and to their successors, the iatrochemists, who applied chemistry to medical uses, experiment was the essential thing; and in their hands true knowl edge rapidly increased. The alchemical ele ments, salt, sulphur and mercury, were still names of properties; but they represented con ceptions which stood closer to reality than the earlier ideas, since they were based upon more exact observations. Speculation had not been dethroned, but it was no longer an absolute ruler.
To trace the history of chemistry during its formative period would be impracticable in an article of the present scope. It is enough to say that the modern distinction between ele ments and compounds was first clearly stated by Robert Boyle in 1661. An element is a sub stance that cannot be further decomposed, but which is obtainable from a compound body, and from which the latter can again be pre pared. He also held that chemical combination consisted in an approximation of the smallest particles of matter, thus adopting the atomic hypothesis which had been current in philosophy from the very earliest times. With these teach ings of Boyle modern chemical theory practi cally began.