Bar iron is at the present day principally manufactured from the pig. The process originally used for this purpose is called refining. The fire in which it is performed is a forge, similar in form and character to that employed in blooming. In blooming, the iron must be reduced, combines with carbon, and is subsequently decarbureted; while in the refining, the latter part of the operation alone remains. In this last process, while the carbon is burning away, the metallic bases of the earths are then oxidated, combine with oxide of iron, and form a vitreous substance. Hence, when it is carefully conducted, by far the greater part of the impurities contained in the cast iron may be removed. Refined iron, if made from ore of equal purity, is not inferior in tenacity to bloomed, and is superior in other respects, being more homogeneous, free from pins, and more easily treated by the smith. As a general rule, it is also less costly, that is to say, the same quantity of charcoal and workmanship will furnish a greater quantity of refined iron. It requires, however, a much greater capital, and the labour of transporting the coal from the greater distances which the increased consumption of a single blast furnace and several refineries will demand, may swell the cost of that article. A bloomery fire does not require more than 2000 acres of woodland, while a blast furnace will use the charcoal of 5000. Thus it happens, that it may be more advantageous to spread a number of bloomeries over a given district of country, than to unite a blast furnace and an equal number of refineries in a single place. The celebrated iron of Sweden and Russia is refined, and our country furnishes iron prepared in the same manner not inferior in quality. The principle objection to the process is the great expense of the fuel employed, in the successive heats to which the iron must be exposed in drawing it into bars, after the processes of conversion and the separation of impurities have been effected. As charcoal became scarce in England, it was attempted to employ coke in lieu of it, in the refineries. This, however, constantly failed, in consequence of the great intensity of the heat, by which the pig was melted suddenly instead of being exposed to the blast, long enough to burn away the carbon. Reverberatory furnaces were next tried, and with partial success, but a combined process has finally been introduced which has been successful and which is called, from a part of the operation, the method of _puddling_.