3. Rotten-stone, 4 oz.; oxalic acid (in fine powder), 1 oz.; sweet oil,
1-1/2 oz.; turpentine, q. s. to make a paste.
_Obs._ The above are used to clean brass-work, when neither varnished nor
lacquered. The first and last are best applied with a little water; the
second with a little spirit of turpentine or sweet oil. Both require
friction with soft leather. See BRASS-WORK, PASTES, &c.
=BRASS PLATING.= _By simple dipping._ A colour resembling brass is given
to small articles of iron or steel by a long stirring in a suspended tub
containing the following solution:--Water, 1 quart; sulphate of copper,
and protochloride of tin crystallised, about 1-5th of an _oz._ each. The
shades are modified by varying the proportions of the two salts.
=BRASS-STAIN.= _Prep._ 1. Sheet-brass (cut into small pieces) is exposed
to a strong heat for 2 or 3 days, then powdered, and again further exposed
in a like manner for several days; the whole is then reduced to fine
powder, and exposed, a third time, to heat, testing it occasionally, to
see if it be sufficiently burnt. When a little of it, fused with glass,
makes the latter swell and froth up, the process is complete. It imparts
to glass a green tint, passing into turquoise.
2. Equal parts of plate-brass and sulphur are stratified together in a
crucible, and calcined, until they become friable; the whole is then
reduced to powder, and exposed to heat as before. This imparts a calcedony
red or yellow tinge to glass by fusion; the precise shade of colour being
modified by the mode of using it.
_Obs._ The common practice in the glass-houses is to conduct the
calcination by exposing the metal, placed on tiles, in the leer or
annealing arch of the furnace; a plan both convenient and economical.
=BRASS'-WORK.= Articles of brass and copper, when not varnished or
lacquered, may be cleaned and polished with sweet oil and tripoli,
rotten-stone, or powdered bath-brick, applied with friction on flannel,
and 'finished off' with leather; due care being taken to ensure the
absence of anything gritty, which would scratch and disfigure the surface
of the metal. A strong solution of oxalic acid in water gives brass a fine
colour. Vitriol and spirits of salts make brass and copper very bright,
but the polish thus obtained soon tarnishes, and the articles consequently
require more frequent cleaning. A strong lye of roche alum and water also
improves the appearance of brass. In all cases where acids or saline
matter has been used, the metal should be at once well rinsed in clean
water, and then wiped dry, and finally dry polished with soft leather.
BRASS INLAID-WORK may be cleaned with tripoli and linseed oil, applied by
a rubber of felt or leather; the whole being afterwards thoroughly rubbed
off, and then finished with clean soft leather. The ornaments of a French
clock, and similar articles, are said to be best cleaned with bread-crumb,
carefully rubbed, so as not to injure the wood-work. ORMOLU CANDLESTICKS,
LAMPS, and BRANCHES, may be cleaned with soap and water. LACQUERED and
GILDED ARTICLES are spoiled by frequent rubbing, and by acids and alkaline
leys.
1. A fine colour may be given to BRASS ORNAMENTS, when not gilt or
lacquered, with a little sal-ammoniac, in fine powder, moistened with soft
water. The articles must be afterwards rubbed dry with bran and whiting.
Another plan is to wash the brass-work with a strong lye of roche alum (1
oz. to water 1 pint), and after rinsing it in clean water and drying it,
to finish it off with fine tripoli. These processes give to brass the
brilliancy of gold. See BRASS-PASTE.
2. A gold varnish for giving a beautiful gilding to brass and bronze
objects is prepared from 16 grams of shell-lac, 4 grams of dragon's blood,
1 gram of turmeric-root, and 332 grams of rectified spirit of wine. The
varnish is thinly stroked over the surface with a sponge, the metal being
warmed over a small coal fire.
The surface at first appears dull, but soon after it appears as if most
beautifully gilded. The ready-prepared spirituous varnish must be
preserved in well-stoppered vessels.--_Dingler's Journal._
=BRASS'ING.= _Syn._ BRASS-COATING. 1. Copper-plates and copper-rods may be
covered with a superficial coating of brass by simply exposing them, in a
heated state, to the fumes given off by melted zinc at a high
temperature. The coated plates and rods are rolled into thin sheets or
drawn into wire. The spurious gold wire of Lyons is said to be made in
this way.
2. Vessels of copper may be coated with brass, internally, by filling them
with water strongly soured with hydrochloric acid, adding some amalgam of
zinc and cream of tartar, and then boiling the whole for a short time.
This plan may be usefully applied in certain cases to copper boilers in
laboratories, and to other purposes.