PAGI 365 363 371 371 372 372 373 CHAPTER I INTRODUCTION § 1. That metals are capable of uniting with each ot form a series of bodies, having more or less the proper their constituents, has long been known, and probabl knowledge has been usefully applied from remote anti The ancients were acquainted with seven metals, viz. silver, mercury, copper, iron, tin, and lead. They kne employed various compounds of antimony, arsenic, and although we have no evidence that these metals were 1 to them in the metallic state. Gold and silver, which occur in nature in the metallic were probably the first metals with which man b acquainted, and as other metals were discovered, esp copper, attempts would doubtless be made to alloy th metals with gold, in consequence of the comparative ra the latter. Copper is also occasionally found "native to persons accustomed to melt the precious metals, there be no difficulty in melting copper and alloying it wit and silver. The Latin word aes in ancient writings som signifies copper, and sometimes brass, so that the two were occasionally confounded together. Pliny says, an ore of aes, termed chalcitis, occurs in Cyprus, whe was first discovered." Here aes obviously means c In another place he says that aes is obtained from a n called cadmia. Now cadmia is the ore known a B present time as calamine, which is chiefly a This substance, when mixed with charco heated for some time in a closed crucible in metallic copper, or with an oxide of copper, fc proper name for brass was aurichalcum, or g it may be inferred that ores of copper and zin smelted together forming brass, as the metal state was probably unknown till the six Pliny describes four different varieties of wha Corinthian copper. 1. White. It resembles silver in lustre excess of that metal. 2. Red. In this kind there is an excess 3. In this kind, gold, silver, and coppe equal proportions. 4. This variety was termed hepatizon, fro liver colour, which gives it its value. Copper was used by the ancients for many to which it is put by the moderns. The a with tin were used in various proportions for statues was composed of 100 parts copper tin. Another mixture was 100 parts copperand 5 parts tin. Culinary pots were made of parts copper and 3 to 4 parts tin. The arms were often made of bronze, which was ren heating and allowing to cool slowly. Tin was in common use in the time of I doubtless the Phoenicians who supplied the this metal, which the former obtained from th and Cornwall. Cassiteros, or tin, is mention In the time of Pliny, tin was used for coating copper and brass vessels. Mercury was used by the Romans for allo and silver to form amalgams, which were used plating, as at the present time, by laying the a base metals, and subsequently volatilising the m leaving a thin coating of the precious metal on Lead was well known to the ancient Egyptians, a as to the Romans, by whom it was termed plumbum n Large quantities of lead were obtained from Spai Britain. Sheet lead and lead piping were used for purposes to those for which they are employed at the time. A mixture of lead and tin was also used as a s Iron was known in very early times, but in compar small quantities, being obtained from meteoric stor easily reducible oxides. Moses speaks of iron being u swords, knives, axes, etc., which seems to imply tha was known at that early period. Homer represents w as armed with bronze swords, and never as usin weapons. Achilles proposes a ball of iron as a valuabl to be contended for in the games, which shows its scar that period. That the Romans were acquainted with as well as with the method of hardening and temper we have abundant evidence. The steel was probably factured direct from iron ore. Steel may be considere alloy of iron and carbon, into which manganese occas enters in small proportion. Thus the ancients knew the six malleable metals an alloys above referred to, but they have left us scant in tion respecting the methods of extracting them from tl It is probable that only those ores of a simple chara those readily acted upon by reducing agents, were em unless the appliances at their disposal and their chemical knowledge were superior to what known warrant us in believing. In the eighteenth century. the investigation nature of alloys began to receive systematic sc attention. Thus Reaumur, an indefatigable French cl concluded that steel was iron impregnated with sulp and saline matters. The word "sulphurous" as used time is nearly synonymous with the present term " tible." At the end of that century, Berthollet con from his own experiments and those of Reaumur the was a compound of iron and carbon. Reaumur also ex C the principle of the method of tinning iron in his Metallurgic Chemistry endeavours t analogy between alloys and solutions, and gives the relative solubilities of metals in each other in silver. He further clearly showed that wi solution of metals in a triple alloy, he under bility of the division of a metal between two solvents. Musschenbroek in the early part of century made some experiments on the t of metals and alloys. He writes of the "ab by which a body resists fracture when acte drawing according to its length." Duhamel of the necessity for making exact experimen with metals which possess a high degree of pu being effected in closed vessels. In the early part of the nineteenth century on alloys became more numerous, and the int them has continued to grow to the present day NATURE OF METALS § 2. The term "metal" indicates a certain chemical elements which have well-defined common, such as metallic lustre, conductiv specific gravity. When separated from their electrolytic action they appear at the negative hence belong to the class of electro-positive properties are by no means equally developed in some instances one or more of these characte absent. On the other hand, there are substanc in character in which some of these properties displayed. Thus, graphite has a metallic lust and silicon are conductors of heat and elect alkali metals are lighter than water. In fact, v elements having strongly marked characteristic unhesitatingly be classed as metallic, there are arsenic, which have properties either metallic of according to the standpoint from which they are v These bodies form a connecting link between meta non-metals, making it impossible to draw a strict 1 demarcation. از The influence of heat upon metals is varied very melt at a low temperature, others require a red h strong red, or a white heat respectively, to melt them. following table by Pouillet will explain the tempe corresponding to different colours : force Incipient red heat corresponds to 525° C. 977° 2 writes alloys, e union earches cited in of the ters in I high nds by le, and These cases; nay be etallic rongly carbon nd the ere are may uch as etallic Metals expand when heated and contract on cooling within certain limits, the expansion is proportional degree of heat. Certain anomalies, however, exist, molten cast-iron expands at the moment of becoming and solidified bismuth occupies a larger space than bi in the liquid state. One of the most distinctive f of a metal is an internal mobility, in virtue of wh shape may be altered by pressure without disruption mass. This property is possessed by metals in degrees, so that the "malleability" or capability of extended by pressure without cracking, and "ductili the capability of being permanently elongated by a stress combined with lateral pressure, are by no means in extent; nor is the order of their malleability the sa for ductility, for the former depends on the softnes tenacity, while the latter is much more dependent on te |