The amalgamating process was also known to the ancients, and Vitruvius (B. C. 27) and Pliny (A. D. 79), describe how mercury was used for separating gold from its impurities. Its use at gold and silver mines was renewed extensively in the sixteenth century. Thus we find that the eighteenth century closed with the knowledge of the smelting furnaces of various kinds, of coke as a fuel in place of charcoal, of furious air blasts driven by steam and other power, of cast iron and cast steel, and of refining, amalgamating, and compounding processes. Looking back, now, from the threshold of the nineteenth century over the path we have thus traced, it will be seen that what had been accomplished in metallurgy was the result of the use of ready means tested by prolonged trials, of experiments more or less lucky in fields in which men were groping, of inventions without the knowledge of the real properties of the materials with which inventors were working or of the unvarying laws which govern their operations. They had accomplished much, but it was the work mainly of empirics. The art preceding the nineteenth century compared with what followed is the difference between experience simply, and experience when combined with hard thinking, which is thus stated by Herschel: “Art is the application of knowledge to a practical end. If the knowledge be merely accumulated experience the art is empirical; but if it is experience reasoned upon and brought under general principles it assumes a higher character and becomes a scientific art.” With the developments, discoveries and inventions in the lines of steam, chemistry and electricity, as elsewhere told, the impetus they gave to the exercise of brain force in every field of nature at the outset of the century, and with their practical aid, the art of metallurgy soon began to expand to greater usefulness, and finally to its present wonderful domain. The subject of metallurgy in this century soon became scientifically treated and its operations classified.