wash it in water, and attach to it a simple cell or weak battery,
and put it into a solution of sulphate of copper. If there is any
part not sufficiently covered with copper by the cyanide solution,
the sulphate will make these parts of a dark colour, which a touch
of the finger will remove. When such is the case, the article must
be taken out, scoured, and put again into the cyanide solution till
perfectly covered. A little practice will render this very easy. The
sulphate solution for covering iron should be prepared by adding
it by degrees a little caustic potash, so long as the precipitate
formed is re-dissolved. This neutralizes a great portion of the
sulphuric acid, and thus the iron is not so readily acted upon.
When the iron is thus coppered, proceed to silver it in the manner
recommended for silvering according to receipt No. 9; or if you want
to put a very heavy coating of silver on it, make use of a strong
battery.


21. SOLDERING FLUID

For mending articles of tin, iron, zinc, copper, and almost all
other metals. Take 2 fl. ounces of muriatic acid, add zinc till
bubbles cease to rise, add 1/2 a teaspoonful of sal-ammoniac and 2
ounces of water. Damp the part you wish to solder with this fluid,
lay on a small piece of lead, and with a piece of hot iron or
soldering iron solder the part.


22. SOLDER FOR TIN

Take of pewter 4 parts, tin 1 part, bismuth 1 part; melt them