The following method for soldering without the use of a soldering iron
is given in the _Techniker_:
The parts to be joined are made to fit accurately, either by filing
or on a lathe. The surfaces are moistened with the soldering fluid, a
smooth piece of tin foil laid on, and the pieces pressed together and
tightly wired. The article is then heated over the fire or by means of
a lamp until the tin foil melts. In this way two pieces of brass can be
soldered together so nicely that the joint can scarcely be found.
With good soft solder, nearly all kinds of soldering can be done over
a lamp without the use of a "copper." If several piaces have to
be soldered on the same piece, it is well to use solder of unlike
fusibility. If the first piece is soldered with fine solder composed of
2 parts of lead, 1 of tin, and 2 of bismuth, there is no danger of its
melting when another place near it is soldered with bismuth solder, made
of 4 parts of lead, 4 of tin, and 1 of bismuth, for their melting points
differ so much that the former will not melt when the latter does. Many
solders do not form any malleable compounds.
In soldering together brass, copper, or iron, hard solder must be
employed; for example, a solder made of equal parts of brass and silver
(!). For iron, copper, or brass of high melting point, a good solder is
obtained by rolling a silver coin out thin, for it furnishes a tenacious
compound, and one that is not too expensive, since silver stretches out
well. Borax is the best flux for hard soldering. It dissolves the oxides
which form on the surface of the metal, and protects it from further
oxidation, so that the solder comes into actual contact with the
surfaces of the metal. For soft soldering, the well-known fluid, made by
saturating equal parts of water and hydrochloric acid with zinc, is to
be used. In using common solder rosin is the cheapest and best flux. It
also has this advantage, that it does not rust the article that it is
used on.--_Deutsche Industrie Zeitung_.
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