Its greatest strength appears to be as follows: 7-16ths of an inch broad, and 5-16ths thick, solid contents 1·40635 inches, will bear a weight of 10,080 pounds; so that if my calculations are correct, it will bear only a pressure of 4,526 pounds in the tube. The loss of strength by heating or softening, being full 10 per cent.
This converted iron, however, will not endure the test of browning by smoke, or, more properly, flame; as the oxygen invariably destroys the appearance of steel in twelve hours after its application. By the old method of staining, it would be as impossible for any man, who was not a judge, to point out the real from the counterfeit, as to discern a copy executed by a clever artist from an original painting by one of the old masters.
But deception is ever fertile in expedients, and an ingenious invention was soon found out to imitate the advantage possessed by the “_smoke brown_,” which they obtain by first browning or staining the barrels very dark. A weak solution of muriatic acid, or spirits of salt, is applied very lightly with a sponge, and the colour is extracted from those portions of the iron left more prominent, by the excessive _pickling_ they are subjected to before staining; they are then immediately dried, scalded with hot water, and the stain is complete; it is a most ingenious imitation.
I have already stated that this iron is very much used in consequence of its cheapness; its cost being only fourpence per pound, while stub twist costs fivepence. It is also easily worked, being considerably softer than any of the above-described kinds of iron.
It may be asked, why so much inferior iron is used, when the difference in the price between the good and the bad is only a penny per pound? The reason is this:--If a barrel filer receive an order for a pair of barrels, he (having probably deceived his customer before, or, at any rate, knowing that he can deceive him without running any risk of detection) sends to the welder sufficient charcoal-iron to forge these barrels. Should the quantity amount to ten pounds, he, of course, saves tenpence. The welder receives two shillings less for welding this description of iron, than for welding stub-twist; so that here is already a saving of 2_s._ 10_d._ At the boring-mill, and the grinding-mill, the charge is also proportionate: the wages of the journeymen are less; so that by imposing on his customer one pair of barrels manufactured of this sort of iron instead of the real stub-twist, he pockets a clear gain of above 9_s._; and should he manufacture one hundred pair of such barrels in the year, it would make at the end no small item in the year’s account of profit.