Previously, I described the method of tinning the bit, etc., with
resin; but before this work on joints can be considered complete, I
find it necessary to speak of tinning the ends of iron pipes, etc.,
which have within the last fifty years been much used in conjunction
with leaden pipes. This is done as follows: Take some spirits of salts
(otherwise known as hydrochloric acid, muriatic acid, hydrogen
chloride, HCl), in a gallipot, and put as much sheet-zinc in it as the
spirit will dissolve; you have then obtained chloride of zinc (ZnCl).
A little care is required when making this, as the acid is decomposed
and is spread about by the discharged hydrogen, and will rust anything
made of iron or steel, such as tools, etc. It also readily absorbs
ammoniacal gas, so that, in fact, sal ammoniac may also be dissolved
in it, or sal ammoniac dissolved in water will answer the purpose of
the chloride of zinc.
Having the killed spirits, as it is sometimes called, ready, file the
end of your iron or bit and plunge this part into the spirits, then
touch your dipped end with some fine solder, and dip it again and
again into the spirits until you have a good tinned face upon your
iron, etc.; next you require a spirit-brush.