258 THE BOOK OF THE LANDED ESTATE. 



recently done, and, if of good quality, the colour in the broken part 

 should be a clear grey, with a bright lustre, and the grains should have 

 an elongated form. When the grains are short, and have a'crystallised 

 appearance, there has been some fault in the forging or in the quality of 

 materials. The strength of this kind of iron varies very much, and this 

 is caused by the two faults already stated namely, either from the 

 presence of some foreign ingredients in the iron, or from some fault in 

 the forging ; and where either occurs, such iron should never be used 

 in positions where great strength is required. Wrought iron may 

 generally be used in any position but a vertical one. In such a position 

 cast iron should be used. Wrought iron is divided into two classes 

 hard and soft. The former is strong, and capable of being easily 

 drawn out. The latter variety is much softer than the other, and yields 

 easily to the hammer. 



Cast iron possesses great strength and durability. It is divided into 

 two kinds white cast iron and grey cast iron. The white variety is very 

 hard and brittle. The grey is tougher than the white, and yet is of a 

 softer nature. The white variety is suitable where hardness is requisite, 

 but not where great strength is necessary, as the grey cast iron is most 

 suitable in such a position. 



The quality of cast iron may easily be tested by striking a portion a 

 heavy blow with a hammer. If of good quality, the iron will yield 

 slightly, and not break. If it breaks, the quality is inferior, as it shows 

 it to be brittle, and this indicates a want of strength. Any ^defects 

 which may be found in cast iron are often caused by the manner in 

 which the moulding takes place. 



Lead is found in Yorkshire, Durham, Cumberland, Derbyshire, and 

 Scotland. The ore is found in beds, generally in the limestone forma- 

 tion. The produce of the English mines is about twenty thousand tons 

 per annum, and that of the Scotch from ten to twelve thousand tons per 

 annum. The price of lead at one time was very high, but since the 

 opening up of extensive mines in Spain, its value has fallen considerably. 

 It is a very valuable material in the erection of buildings, such as 

 piping, soldering, guttering of the roof, and other purposes. 



Zinc is an ore also found in this country. It is chiefly found in the 

 limestone formations. It is naturally hard and brittle, but it can be 

 rendered soft and useful for building purposes. It is found very valu- 

 able in the making of roofing, baths, cisterns, pipes, &c. 



Copper is a very durable material, and when made into thin sheets is 

 found useful, and is not much affected by the atmosphere. 



Brass is a combination of zinc and copper. British brass is made of 

 about sixty-six parts of copper and thirty-three of zinc. 



