Before silver plating, such metals as iron, lead, pewter, zinc,
must be coated with copper in the alkaline copper bath described,
and then treated as copper. On brass, copper, German silver,
nickel and such metals, silver can be plated direct. The deposit
of silver will be dull and must be polished. The best method is to
use a revolving scratch brush; if one does not possess a buffing
machine, a hand scratch brush is good. Take quick, light strokes.
Polish the articles finally with ordinary plate powder.
The sketch shows how to suspend the articles in the plating-bath.
If accumulators are used, which is advised, be sure to connect the
positive (or red) terminal to the piece of silver hanging in the
bath, and the negative (or black) terminal to the article to be
plated. Where Bunsen cells are used, the carbon terminal takes the
place of the positive terminal of the accumulator. --Model
Engineer.
** An Ingenious Electric Lock for a Sliding Door [89]
The apparatus shown in Fig. 1 not only unlocks, but opens the
door, also, by simply pressing the key in the keyhole.
In rigging it to a sliding door, the materials required are: Three
flat pulleys, an old electric bell or buzzer, about 25 ft.
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