ather brown than yellowish
brown, i.e. of the colour of wet wash-leather, the removal, followed
by scratch-brushing, may be repeated, and for nearly all laboratory
purposes, the articles are now fully gilt.

The coating of gold deposited from a hot cyanide solution is spongy in
the extreme, and if the maximum wear-resisting effect is to be
obtained, it is advisable to burnish the gold rather than to rely upon
the scratch brush alone.

If the area of the cathode exceeds that of the anode the solution is
said to grow weaker, and vice versa. This may be remedied in the
former case by an obvious readjustment; the latter introduces no
difficulty so far as I know except when plating iron or steel.

The student need not be troubled at the poor appearance of the deposit
before it is scratch-brushed. Heavy gold deposits are almost always
dull, not to say dirty, in appearance till the burnisher or scratch
brush is applied. On the other hand, the deposit ought not to get
anything like black in colour.

The following indications of defects may be noted--they are taken from
Gore. I have never been really troubled with them.

The deposit is blackish. This is caused by too strong a current in
too weak a bath. This may be remedied to some extent by stirring or
keeping the cathode in motion. The obvious remedy is to add a little
cyanide of gold.

The gold anode gets incrusted. This is a sign that the bath is
deficient in potassium cyanide. The gold anode gets black and gives
off gas. The solution is deficient in cyanide, and too large a
current is being passed.

If a bright surface is desired direct from the bath, some caustic
potash (say 2 per cent) may, according to Gore, be added, or the
articles may be plated only slightly by using a weak current and
taking them out directly they show signs of getting dull. By a weak
current I mean one of about five amperes per square foot.

The deposit is said to be denser if the solution be heated as
directed; but the bath will gild, though not quite so freely when
cold.

To gild iron or steel directly, dilute the bath as above recommended
some five or six times, add about 1 per cent of potassium cyanide, and
gild with a very weak current (say two or three amperes per square
foot) in the cold. Frequent scratch-brushing will be found requisite
to secure proper adherence.

It is generally recommended to gild brass or German silver in
solutions which are rather weak, but