As lead slowly oxidizes at a red heat, two methods may be used to prevent it. One is to cover the surface of the lead with a layer of fine charcoal or even wood ashes. Another and a better plan, when the work will admit of its use, is to float on the top of the lead a thin iron plate, fitting the vessel in which the lead is contained, but having a hole in the centre or on one side, as most convenient, and large enough to readily admit the articles to be tempered or softened.
Test for Good Steel.—Break the bar of steel and observe the grain, which in good steel should be fine and present a silvery look, with sometimes an exfoliated or leaf-like appearance. One of the best tests of steel is to make a cold chisel from the bar to be tested, and when carefully tempered (be careful not to overheat), try it upon a piece of wrought iron bar. The blows given will pretty correctly tell its tenacity and capability of holding temper. Remember the temper you gave it, and if it proves tough and serviceable, take this temper as a guide and temper other tools in like manner. Inferior steel is easily broken, and the fracture presents a dull, even appearance, which may very appropriately be termed a lifeless look.
Etching on Steel.—Make an etching solution by pulverizing together sulphate of copper, one ounce; alum, one-quarter ounce, and common salt, one-half teaspoonful. Add one gill strong vinegar and twenty drops nitric acid. Stir till thoroughly dissolved. Polish up the metal to be etched, and then cover its polished surface with a thin coating of bees-wax. This can be accomplished with neatness by simply heating the metal till the wax flows evenly over its surface. Now draw upon the wax, cutting cleanly through to the steel the figure you wish to etch; then cover the figure so prepared with the etching solution, and let stand for a short time, depending upon the depth of cut desired. Finally rinse off with clear water, and then remove the bees-wax. It will be found that the solution has cut into the surface of the steel wherever exposed, leaving untouched all parts covered by the wax.
Very good etching can be done by applying, on the foregoing plan, nitric acid alone. Etching offers a good method of cutting a man’s name on his gun or pistol. It works on silver or brass the same.
CHAPTER XII.
ON WORKING IN SILVER, COPPER AND BRASS.
To Forge Silver.—The gunsmith will not have much to do with silver in the work of his trade, though instances may occur now and then when he will be called upon to make or repair mountings or ornaments for gun-stocks formed of this metal, and also foresights, particularly for the old fashioned Kentucky rifle.
In shaping silver under the hammer no heat will be necessary at the hammering—it would do no good. The metal is so malleable that it may be drawn into almost any shape by simply hammering cold. The only trouble liable to come up in this kind of work will be the hardening of the metal under the influence of the hammer; but this trouble may be pretty effectually removed by heating the silver to redness, and then letting it cool gradually of itself. Care must be taken not to heat it too much above the first appearance of red, as it melts quite easily.
To Polish Silver.—File it down to the shape desired, then dress with a fine file; then work over thoroughly with a burnisher. Next buff it off with rotten stone, and if a particularly fine finish is desired buff again with rouge.
Light Plate for Copper or Brass.—Dissolve silver in nitric acid by the assistance of heat; put some pieces of copper into the solution and immediately the silver will be precipitated. With fifteen or twenty grains of the precipitate thus obtained mix half a drachm of alum and two drachms each of tartar and common salt. Pulverize well together. Having thoroughly cleaned the surface to be plated, rub it well and hard with the mixture, using a bit of chamois skin, until it presents a white appearance. Next polish off with soft leather until bright.