250 Chemistry. [Lecture 32. 



durable. Its alloys with tin will be afterwards 

 noticed. Combined with zinc in the proportion 

 of three parts of copper, by weight, to one of 

 zinc, it forms that beautiful compound brass, 

 which, by the addition of other metals, or by 

 varying the proportions, may be made of va- 

 rious colours, from that of pinchbeck to the 

 ligtest coloured brass. 



6th. Iron, the most useful of metals, is hap- 

 pily the most abundant, and the most friendly 

 to the human constitution. The working of it, 

 unlike that of lead, copper, &c., is perfectly 

 consistent with health. Iron was known before 

 the time of Moses. It has a peculiar taste and 

 smell, and is the toughest of metals, but is less 

 malleable than either gold or silver, or even 

 copper. Its hardness in the state of steel, 

 which is iron combined with carbon, is well 

 known. 



The ores of iron are oxides of that metal ge- 

 nerally mixed with earth. The metal is sepa- 

 rated by fusion with charcoal. In its fluid state 

 it is run into moulds, and is then called pig or 

 cast iron. As this metal, however, has a strong- 

 attraction for c'arbon, it is not so pure after 

 fusion as other metals. Cast iron, indeed, con- 

 tains a large quantity of carbon, imbibed from 

 the charcoal, with which it is fused, as well as 

 other impurities. To expel these, the pig iron 

 is again heated red-hot, and beaten with immense 



