288 Mr. J. Taylor's Lectures on Metallurgy. 



which is a quality that some of them have of uniting into a soHd 

 state by a partial fusion of the surfaces: thus wrought iron is 

 joined together, or iron is united to steel, which enables the 

 workman to produce many most useful combinations. 



4thly. Of all the properties, perhaps extensibility is the 

 most extraordinary, and it adapts the metals most for uses for 

 which substitutes could hardly be found. The following pro- 

 cesses depend upon this property. 



Forging; which is appUed to iron, steel, and copper. 



Laminating or Rolling; by which plates or sheets of many 

 metals are produced, and by vai'ying the process we obtain 

 rods and bars. 



Wire-drawing is applied to metals which have considerable 

 tenacity, and is accomplished by pulling rods successively 

 through holes, each smaller than the last. Pipes are formed of 

 soft metals, such as lead, tin and copper, by a somewhat simi- 

 lar operation. 



Coining is an art also dependent on the ductility of metals, 

 and seems to have been very anciently practised. 



A similar process applied to thin plates of metals is called 

 stamping, by which many beautiful forms in plated goods and 

 brass ornaments are produced. 



Plating, particularly of silver upon copper or brass, is prin- 

 cipally performed by applying the two metals to each other, 

 and laminating them together, so that a perfect contact is pro- 

 duced. And gilt wire is formed by drawing a rod of silver 

 which has been coated with gold, and by which the latter metal 

 is attenuated to an almost incredible degree. 



The tenacity of metals makes them most suitable for many 

 important purposes ; such as chains, wires, steam-boilers and 

 other strong vessels, guns, &c. 



5thl}^ By taking advantage of their penetrability and their 

 different degrees of hardness, we avail ourselves of all the 

 purposes which may be attained by the processes of turning, 

 boring, filuig, cutting or chipping, often called chasing, 

 planing, engraving, polishing and grinding. 



6th. The quality of elasticity which many metals possess in 

 a remarkable manner, gives us a great variety of our best 

 springs for various important purposes ; and under the same 

 head we may arrange the use of metal for musical strings or 

 wires, and bells. 



7th. From the affinity of the metals for each other we de- 

 rive the power of making many compounds called Alloys, and 

 which either possess qualities intermediate between their con- 

 stituents, or often differing from both; thus rendering it possi- 

 ble for us, if we do not find a metal suited to our purpose, 



to 



