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OK ENGINEERING FORMULAE.
Workshop Recipes— contiwicd.
Galvanizing Iron. •
1. Pickle the article six or eight hours in water
containing about 1 per cent, of sulphuric acid held
in wooden vessels; the acid requires to be renewed
from time to time, according to the quantity of
irou pickled.
2. After pickling scour and wash well in clean
water.
3. Keep the article under clean water (in which
a little fresh burnt lime has been stirred) until
ready for the next process.
4. Immerse in chloride of zinc for one or two
minutes until a skin of fine bubbles is formed on
the surface. Chloride of zinc may be formed by
saturating hydrochloric acid with metallic zinc
until effervescence ceases, then decanting and
adding a little sal-ammoniac.
5. Dry the article on a heated iron plate, then
immprst: it in a bath of molten (not glowing) zinc
until it acquires the temperature of the zinc bath.
The surface of the molten ziuo should be protected
by sal-ammoniac or some other substance. In
some cases there is a partition at the surface of
the bath, one portion of the surface being pro-
tected with sal-ammoniac, the other with a layer
of charcoal,
6. Beat the article while hot, to remove the
excess of zinc.