The mixture of a portion of steel with the stubs having clearly shown an improvement, an increased proportion has been adopted by various makers: we have had as high as three-fourths of steel to one of iron. Where proper attention is paid to the clipping of the steel to pieces, corresponding with the stubs, and properly mixing the whole, welding and forging by the heavy hammer, reducing by a tilt and rolling down to the smallest description of rod, a most excellent, tenacious, and dense body of iron is thus obtained; while, by cutting into lengths of six inches, bundling a number together, and re-welding them into a bar, an increased density and tenacity is gained, by an increase in quantity, and an elongation of the fibrous system. Any description of barrel, of this iron, if made with a moderate degree of care and attention, is considerably stronger than any explosive fluid ever yet compounded could burst, under any circumstances bordering on _fair experiment_. The great advantage derived from welding on the bed of an air-furnace, arises from an absence of the minute portions of charcoal, of either wood or coal, as the case may be. Millions of these very minute portions are imbedded in the midst of the metal in every part. They are enclosed in cells originally of their own dimensions, but are drawn out with the fibres to an indefinite extent, forming a system of tubes that may be compared to the capillary system in trees, and making the iron of a spungy, compressible nature. It is the absence of these particles of charcoal that gives part of the superiority to steel as now made for gun-barrels; and the existence of a portion of them causes the inferiority of all other kinds of iron. In a chemical analysis of iron, a large portion of crude coal-charcoal or wood-charcoal is found, according as either has been used during the manufacture. This is not of course given as so much carbon in the result, though the injury is equally detrimental as an excess of carbon is to the goodness of the metal; for it renders the whole porous, and liable to attract moisture and induce oxidation. It must be kept prominently in view, and clearly comprehended, that the denser the body of metal, the less the liability to oxidise, or in other words _rust_; and here is the one great preservative principle in good iron: “it is the fibre of dense cocoa-wood, compared with that of willow or saugh.” In all situations and for all purposes, where iron is liable to sudden changes of either heat or cold, wet or dry, the very best of iron should be obtained; as it will be less affected by the changes of temperature, and amply repay by its durability the extra cost in the first instance.