r way to tin the iron that is in common use is to rub the
point of a hot iron on a piece of sal-ammoniac, or dip the hot iron
in reduced muriatic acid, then rub the stick of solder on the iron.
The use of muriatic acid in tinning the iron is not recommended. In
the first place, it is not always possible to carry it, and in the
second place it eats holes in the surface of iron, which makes it
necessary to file and smooth the surfaces again. The constant use
of muriatic acid on the copper soon wears it away and makes it
unfit for use. Rosin is easily carried and applied and is by far
the best to use in regular work.

POINTS TO REMEMBER IN THE CARE OF THE SOLDERING IRON.--

_First_, proper tinning is absolutely necessary for rapid and
good work.

_Second_, do not allow the iron to heat red hot.

_Third_, keep the point of the iron properly shaped.

_Fourth_, use the same flux in tinning as is to be used in
soldering.

_Fifth_, when filing iron, file as little as possible.

_Sixth_, keep in use two irons of the same size.

FLUX

A flux is used to clean the surfaces of joints and seams to be
soldered, also to keep them from oxidizing and to help the metals
to fuse.

The following list gives the names of various fluxes in common use,
how they are applied, and on what material they are most commonly
used:

Flux How applied Used on

Rosin Sprinkled on Lead, tin, and brass
Tallow Melted Lead and brass
Muriatic acid (reduced) With swab Copper, galvanized iron
and brass
Muriatic acid (raw) With swab Dirty galvanized iron

ROSIN.--Rosin is purchased by the pound and comes in chunks. It is
very brittle and powders easily. Plumbers generally take a piece of
1-1/4 N. P. brass tubing, solder a trap screw in one end and a
cone-shaped piece of copper on the other. The point of the cone is
left open. Rosin is put into this tube and is easily sprinkled on
work when needed.

TALLOW.--A plumber's _tallow candle_ answers the purpose for tallow
flux. Some plumbers carry a can for the tallow, making it cleaner
to handle.

MURIATIC ACID.--Muriatic acid or hydrochloric acid is used both raw
and reduced. Raw acid is not diluted or reduced. Reduced acid is
made as follows: Put some zinc chips in a lead receptacle