ng,
and if a little potassium cyanide be added.

For purposes of instrument construction, however, a thin coat of
silver is seldom to be recommended, on account of its liability to
tarnish and its rapid destruction when any attempt is made to repolish
it. For these reasons, nickel or gold plating is much to be
preferred.

Sec. 134. Gilding.

This art deserves to be much more widely practised than is usual in
laboratories. Regarded as a means of preserving brass, copper, or
steel, it is not appreciably more "time robbing" than lacquering, and
gives infinitely better results. Moreover, it is not much more
expensive. Strange as it may seem, the costliness of gilding seldom
lies in the value of the gold deposited; the chief cost is in the
chemicals employed to clean the work, and in interest on the not
inconsiderable outlay on the solution and anode.

The easiest metal to gild is silver, and it is not unusual to give
base metals a thin coating of silver or copper, or both, one after the
other, before gilding, in order to secure uniformity. To illustrate
the virtue of a thin layer of gold, I will mention the following
experiment. About three years ago I learned for the first time that
to "clean" the silver used in a small household required at least an
hour's labour per diem. I further ascertained that most of this time
is spent on the polishing part of the process.

As this seemed a waste of labour, I decided to try the effect of
gilding. In order to give the proposal a fair trial I gilt the
following articles: half a dozen table spoons and forks, a dozen
dessert forks and spoons, and a dozen tea spoons. These were all
common electroplated ware. They were weighed before and after
gilding, and it was with difficulty that the increase of weight was
detected, even though a fine bullion balance was employed. On
calculating back to money, it appeared that the value of the gold
deposited was about threepence. Assuming that an equal weight of
silver had been accidentally dissolved by the free cyanide during the
plating--which is unlikely--the total amount of gold deposited would
be worth, say, sixpence.

After three years' continuous use the gilding is still perfect, except
at the points on which the spoons and forks rest, where it is
certainly rather shabby. Meanwhile the "gold" plate only requires to
be washed with hot water and soap to keep it in perfect order, a much
more cleanly and expeditious process