224 ON THE WING. 



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 por- 

 tions 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 spongy, .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 j 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 ren- 

 ders 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 oxidize, or in 



