UNIVERSITY OF CALIFORNIA. THE PRACTICAL METAL-WORKER'S ASSISTANT. CHAPTER I. ON METALLURGIC CHEMISTRY. THE USEFUL METALS AND METALLIC ORES DEFINED.-Of sixtyfour simple or elementary material bodies, no less than fifty or fifty-one are metallic. We shall not enter upon the characteristics which serve to define a metal-that more especially belongs to the functions of a chemical treatise; but taking it for granted that the attributes of a metal are sufficiently well agreed upon for popular use, we shall proceed to offer a few general remarks on their useful properties, of which rigidity, cohesion, tenacity, and durability are the most remarkable, although many more are conjoined in variable degrees. The ancients were only acquainted with seven metals, whereas we know of fifty or fifty-one; nevertheless those now in most general requisition, and to which the appellation "useful metals" most peculiarly belongs, were all known to the ancients. Methods of working them, however, and new sources from which to obtain them, have multiplied so much in modern times as almost to rank in importance with the discovery of the existence of a new metal. Metals are either found native-that is to say, in the condition of obvious metallic existence-or they are combined with other substances, so as to lose all obvious evidence of their metallic constitution. The latter condition is by far the more frequent; and to this fact more than any other the consecutive history of special metallic discovery is attributable. This circumstance leads us to an important chemical consideration, having reference to the comparative tendencies of different metals to combine with the nonmetallic elements, and to lose by such combination their obvious metallic form. The term "noble metals," though applied to gold and silver in ages when the principles of chemical science were un- . known, has nevertheless a positive chemical significance. Modern discovery has added platinum to the list; and they all agree in the property of being very slow to combine with any foreign material save other metals. Hence it is that they are so frequently found (gold and platinum almost universally) in the native or metallic state, united frequently with other metals, it is true, but still exhibiting the metallic aspect. If the noble metals existed in larger quantity, offered equal facility for working them, and equal hardness after being worked, their slowness to unite with oxygen would render them, more than all others, deserving of the appellation of "useful metals;" but, being deficient in these qualities, notwithstanding their nobility, they must yield the palm to iron, tin, copper, zinc, and lead, in the first instance, and perhaps to mercury or quicksilver, and bismuth also; considering the various applications of these metals to the useful arts of life. The progress of metallurgy and of smelting operations demonstrates how great may be the advance of arts based upon scientific principles, without these principles being understood. The production and utilization of metals are intimately allied with chemistry; and deriving such immense advantages from the application of chemical principles at this time, it is extraordinary to reflect on the comparative excellence to which the art of working several useful metals had arrived, before the aggregation of chemical facts and principles to which the denomination science" is alone justly due, had dawned. Chemical science may be indeed said to rest on an historical basis of metallurgic aspirations, and metallurgic empiricism. Coeval with the earliest historical records, some metals were worked, and the operations of working involved the influence of chemical laws; yet the simplest principles of chemistry had not then dawned. At later periods it was alchemy-the vague hallucination of making gold-which prompted men to undertake investigations fruitful of chemical deductions, to be marshalled into a science hereafter. Metallurgy, then, may justly lay claim to be considered the fountain source of chemistry; and the subsequent development of the science to the art, might supply the theme of argument in favor of empiricism over intellectualism, if, at various periods within the last two hundred years, the miner and the metallurgist, by their devotion to chemistry, and the chemist by his successful labors in the practical fields of mining and smelting, had not demonstrated how mutual is the relation between theory and practice, how inseparable for good, how redundant of advantages the one to the other. Metallurgy (accepting the word in its most extensive signification) derives its best processes, and not unfrequently its best practical aids, from a due appreciation of chemical principles. And, on the other hand, the mere theoretical chemist derives a useful lesson of the necessity of checking his theoretical deductions by facts, as they are found to be, by attending to some of the teachings of metallurgy. Several metallic operations there are, the success of which is at variance with all the theoretical indications of chemistry. "Corpora non agunt nisi fluida" was a chemical dictum of received universality; nevertheless, the practice of annealing, or the conversion of iron into steel by combination with carbon, is a practical refutation of the universality. This process consists in the heating together iron bars and wood-charcoal in a suitable furnace. Both iron and carbon are here brought together in the solid state; both may be said to be devoid of volatility, and almost of liquidity; nevertheless, in violation of the formerly received canon, combination ensues, and steel is made. A similar disaccordance between the indications of theory, and the teachings of practice, is illustrated by the hot-blast operation, introduced some years ago in the practice of iron smelting. On the other hand, chemistry illuminates many dark recesses in the field of metallic empiricism, and points to facts, the existence of which would not have been suspected. It is unnecessary, however, further to expatiate on the advantages which the metal-worker derives from the knowledge and application of chemical theory, the connection being now admitted by none more readily than by the practical metallurgist. HISTORY OF METALLURGY.-In illustration of the mutual dependences of a branch of practical metallurgy and chemical science, it may be here not unadvisable to anticipate the contents of the monographs which especially deal with special metals, and to trace cursorily the various phases which the production of the metal iron has undergone. From one of several metalliferous sources this useful body has been produced from perhaps the earliest historical periods. True though it be that the ancient Greeks, at the very earliest period of their history, do not seem to have been acquainted with the existence of, far less the method of working, iron-yet we read of both in Scripture; and there is good reason to believe that anterior to the earliest historical record of the Greeks, iron, and the processes of manufacturing it, were known in China and Hindostan. We know, too, that immutability is impressed on all the processes of the East; whence it is not unreasonable to infer that the processes of rude iron manufacture now followed in Asia, are types of, if not identical with the processes followed there in times long passed. What are these processes? What is their general characteristic? What are the principles involved? What is the result? One general scheme of appliances pervades them all. The object is to begin with an ore of iron capable of reduction by charcoal fuel, and of yielding a semi-fluid result, which the subsequent process of welding fashions into shape. Even in this simple form of iron-smelting, a good deal of latent chemistry is involved; but the fullest acquaintance with chemistry could not improve the practice of iron-smelting, as followed by the Persians and Hindoos, if limited to the means at their command, and the ends proposed to be gained. The iron manufacture of England, as prosecuted in bloomaries by the aid of charcoal fuel was only a modification of the Persian method, and conducted almost as empirically. No sooner was the practice of iron-smelt ing by charcoal fuel abolished, and pit-coal, or its immediate derivative coke, introduced, then an application of chemical principles became necessary. How far these applications resulted in empirical tentative experiments, or in the suggestions of chemical teaching, it would not be possible at this time to decide; but the historian of the iron manufacture has not to pursue his labors much further before the reaction of chemical knowledge on mere empiricism is made evident. Practice demonstrated the fact that coal-smelted iron was inferior to charcoal-smelted iron; but practice could not say wherefore, until science came to the ironsmelter's aid, making known to him the composition of pit-coal, proving that it contained many foreign substances, which found their way into the smelted iron, and injured its quality. Analysis of coal-smelted iron demonstrated the existence of both sulphur and phosphorus incorporated with it, demonstrated moreover that, caeteris paribus, the amount of deterioration of the iron was in direct proportion to the quantity of these elements which it contained. Chemistry next began to shed a light on the nature and property of fluxes, in showing how a mixture of several iron ores might conduce to yield a more fluid mass in the furnace than any one ore by itself. The next chemical glimmering fell on the apprehension of Cort, that Nestor of the British iron trade, and led to his improvements in the processes of refining and puddling, the results of which, combined with the rolling aid devised by his mechanical genius, eventuated in Britain, supplying iron in large quantities to other countries, from which she had heretofore obtained that metal. It was our proposition, that as the operations of metallurgy (accepting the word in its largest sense) came down to our own times, the reaction of theoretical chemistry upon its practical development has continued to increase. Whilst the supply of British wood-charcoal lasted, and before the demand for iron became so enormous, as it has from the beginning of the last century, charcoal answered its purpose tolerably well. The iron manufactured by it resulted in small quantity; but, by comparison with coal, or coke-smelted iron, it was pure. England, however, in course of time became deforested in the neighborhood of the existing iron-works, the source of wood-charcoal thus failed, and pit-coal of necessity was obliged to be employed henceforth for the production of iron. Simultaneously with its adoption, the clay iron-stone began to supply the place, to a variable extent, with iron ore. The result was attended with both advantages and defects. Iron admitted of being obtained in enormous quantities from these sources; but it had no longer the purity of the charcoal-iron of heretofore. Not only was the quality of the result deteriorated by the presence of impurities originally contained in the ore, but |