certain tropical plants of a red
colour, especially of the tree _Pterocarpus draco_. After the juice is
extracted, it is reduced to a powder by evaporation. It is used for
darkening mahogany, colouring varnishes or polishes, etc., and for
staining marble. Chemists also use it in preparing tinctures and tooth
powders.

=Shellac=--or, more properly, _gum-lac_--is a resinous substance
obtained from the Bihar-tree, and also from the _Ficus Indica_, or
Banyan-tree. It exudes when the branches are pierced by an insect called
the _Coccus ficus_. The twigs encrusted with the resin in its natural
state is called Stick-lac. When the resin is broken off the twigs,
powdered, and rubbed with water, a good deal of the red colouring matter
is dissolved, and the granular resin left is called seed-lac; and when
melted, strained, and spread into thin plates it is called shellac, and
is prepared in various ways and known by the names of button, garnet,
liver, orange, ruby, thread, etc., and is used for many purposes in the
arts. Shellac forms the principal ingredient for polishes and spirit
varnishes. Red sealing-wax is composed of shellac, Venice turpentine,
and vermilion red; for the black sealing-wax ivory-black is used instead
of the vermilion. Shellac is soluble in alcohol, and in many acids and
alkalies. Lac-dye is the red colour from the stick-lac dissolved by
water and evaporated to dryness. The dye, however, is principally from
the shrivelled-up body of the insect of the Stick-lac.

Shellac is produced in the largest quantity and the best quality in
Bengal, Assam, and Burmah. The chief seat of manufacture is Calcutta,
where the native manufacturers are accused of adulterating it with resin
to a considerable extent. The best customers are Great Britain and the
United States, though the demand in the Italian markets appears to be on
the increase.

=Amber= is a yellow, semi-transparent, fossil resin; hard but brittle,
and easily cut with a knife; tasteless, and without smell, except when
pounded or heated, and then it emits a fragrant odour. It has
considerable lustre; becomes highly electric by friction; and will burn
with a yellow flame. It is found in nodules of various sizes in alluvial
soils, or on the seashore in many places, particularly on the shores of
the Baltic. Amber is much employed for ornamental purposes, and is also
used in the manufacture of amber-varnish. It will not dissolve in
alcohol, but yields to the co