In the manufacture of cast iron then, coke gives iron better suited for small castings, for those which require turning or filing, and yields a far greater quantity from a furnace. Hence arises the very great superiority which Great Britain has, until recently, possessed over most other countries, in those fabrics in which these qualities are valuable; and hence it has been found until lately, in this country, hardly possible to manufacture fine machinery that requires workmanship after it is cast, without the aid of the higher qualities of Scotch iron, which, in these qualities, exceeds even the English. Recently, however, iron fully equal to the best Scotch, but like it wanting in tenacity, has been manufactured at the Bennington furnace in Vermont:--so also at the Greenwood furnace in Orange county, N. Y., and at West Point, iron approaching to the Scotch in softness, but very superior in strength, has been produced. In these cases, the height of the furnace has been carried up to the limits we have before laid down, and powerful blowing cylinders substituted for the ancient bellows. When the pig iron is to be used for re-casting, every effort ought to be used to obtain it of the deepest possible colour. This, as may be seen from what has been already stated, will be effected by keeping the furnace at the highest possible temperature, and exposing the metal to it a sufficient length of time. In effecting this, however, certain defects may arise:--thus a longer exposure to a high heat, will cause the reduction of other oxides that may be present, as of manganese and the metallic bases of the earths; and the iron in becoming more soft, and approaching in fact more nearly to the form of the pure metal, will combine and form alloys with these bases. In this way, it will, as has been stated, become cold short; and to this may be attributed the want of strength in the greater part, if not all, of the British iron. The use of coke as a fuel, tends to increase this defect, in consequence of the great quantity of earthy matter it contains.