nd after boiling and evaporation the liquor
assumes the consistency of tar; but when cold it hardens, and is formed
into small squares. It is extensively used by tanners in place of oak
bark.

=Thus.=--Thus is the resin which exudes from the spruce-fir, and is used
by some polishers in the making of polishes and varnishes.

=Sandarach= is the produce of the _Thuya articulata_ of Barbary. It
occurs in small pale yellow scales, slightly acid, and is soluble in
alcohol; it is used in both polishes and varnishes.

=Mastic= exudes from the mastic-tree (_Pistacia lentiscus_), and is
principally obtained from Chios, in the Grecian Archipelago. It runs
freely when an incision is made in the body of the tree, but not
otherwise. It occurs in the form of nearly colourless and transparent
tears of a faint smell, and is soluble in alcohol as well as oil of
turpentine, forming a rapidly-drying but alterable varnish, which
becomes brittle and dark-coloured by age.

=Benzoin.=--This is the produce of the American tree _Laurus benzoin_,
and also of the _Styrax benzoin_ of Sumatra, which is called "gum
benjamin"; it is used in polishes and varnishes, and as a cosmetic, and
is also burnt as incense in Catholic churches.

=Copal= is one of the most valuable of gums, and is furnished by many
countries in the districts of Africa explored by Mr. H. M. Stanley, the
discoverer of Livingstone. Copal is found in a fossil state in very
large quantities. The natives collect the gum by searching in the sandy
soil, mostly in the hilly districts, the country being almost barren,
with no large tree except the Adansonia, and occasionally a few thorny
bushes.

The gum is dug out of the earth by the copal gatherers at various
depths, from two or three to ten or more feet, in a manner resembling
gold-digging; and great excitement appears when a good amount is
discovered. The gum is found in various shapes and sizes, resembling a
hen's egg, a flat cake, a child's head, etc. There are three kinds,
yellow, red, and whitish; and the first furnishes the best varnish and
fetches the highest price from the dealers. Many of the natives assert
that the copal still grows on different trees, and that it acquires its
excellent qualities as a resin by dropping off and sinking several feet
into the soil, whereby it is cleansed, and obtains, after a lapse of
many years, its hardness, inflammability, and transparency.

=Dragon's Blood= is the juice of