Welding Composition for iron or steel, is made of borax 10 parts, sal ammoniac 1 part; to be melted, run out on an iron plate, and, when cold, pounded for use.

Cast Steel.—­A mixture of 100 parts of soft iron, and two of lamp-soot, melts as easily as ordinary steel—­more easily than iron.  This is a ready way of making cast-steel where great heat cannot be obtained.

Case-hardening is the name given to a simple process, by which the outside of iron may be turned into steel.  Small tools, fish-hooks, and keys, etc., are usually made of iron; they are fashioned first, and case-hardened afterwards.  There are good reasons for this:  first, because it is the cheapest way of making them; and secondly, because while steel is hard, iron is tough; and anything made of iron and coated with steel, combines some of the advantages of both metals.  The civilised method of case-hardening, is to brighten up the iron and to cover it with prussiate of potash, either powdered or made into a paste.  The iron is then heated, until the prussiate of potash has burned away:  this operation is repeated three or four times.  Finally, the iron, now covered with a thin layer of steel, is hardened by quenching it in water.  In default of prussiate of potash, animal or even vegetable charcoal may be used, but the latter is a very imperfect substitute.  To make animal charcoal, take a scrap of leather, hide, hoof, horn, flesh, blood—­anything, in fact, that has animal matter in it; dry it into hard chips like charcoal, before a fire, and powder it.  Put the iron that is to be case-hardened, with some of this charcoal round it, into the midst of a lump of loam.  This is first placed near the fire to harden, and then quite into it, where it should be allowed to slowly attain a blood-red heat, but no higher.  Then, break open the lump, take out the iron, and drop it into water to harden.

Lead is very useful to a traveller, for he always has bullets, which furnish the supply of the metal, and it is so fusible that he can readily melt and cast it into any required shape; using wood, or paper, partly buried in the earth, for his mould.  If a small portion of the lead remain unmelted in the ladle, the fluid is sure not to burn the mould.  By attending to this a wooden mould may be used scores of times.

[Sketches as described below].

Fig. 1 shows how to cast a leaden plate, which would be useful for inscriptions, for notices to other parties.  If minced into squares, it would make a substitute for slugs.  The figure represents two flat pieces of wood, enclosing a folded piece of paper, and partly buried in the earth the lead is to be poured into the paper.

To make a mould for a pencil, or a rod which may be cut into short lengths for slugs, roll up a piece of paper as shown in fig. 2, and bury it in the earth:  reeds, when they are to be obtained, make a stronger mould than paper.

To cast a lamp, a bottle, or other hollow article, use a cylinder of paper, buried in the ground, as in fig. 3, and hold a stick fast in the middle, while the lead is poured round.