For this purpose alkaline liquors are not to be used; for while they
clean the gold they corrode the silk, and change or discharge its
colour. Soap also alters the shade, and even the species of certain
colours. But, spirit of wine may be used without any danger of
its injuring either colour or quality; and, in many cases, proves
as effectual for restoring the lustre of gold, as the corrosive
detergents. But, though spirit of wine is the most innocent material
employed for this purpose, it is not in all cases proper. The golden
covering may be in some parts worn off; or the base metal, with which
it has been alloyed, may be corroded by the air, so as to leave the
particles of gold disunited; while the silver underneath, tarnished
to a yellow hue, may continue a tolerable colour to the whole: so it
is apparent that the removal of the tarnish would be prejudicial, and
make the lace or embroidery less like gold than it was before.