East African Copal. It is found imbedded in the earth at
a depth not greater than four feet over a wide belt of the mainland
coast of Zanzibar, on tracts where not a single tree now grows. It
occurs in lumps from the size of small pebbles to pieces weighing four
or five pounds. The supply is said to be practically inexhaustible.

As to the manufacture of the Copal varnishes: first of all, a high
grade oil is boiled at a high temperature, with different materials
to oxidize it; for instance, red lead or oxide of manganese. The heat
throws off the oxygen from the red lead or manganese. The oxygen is
absorbed by the linseed oil, which is then put away to settle and age.
When a batch of varnish is made, the gums are melted in a large kettle
and then the requisite amount of oil is added and these carefully
boiled together. This is removed from the fire and cooled down to a
point, where turpentine can be added without volatilizing. These are
thoroly mixed and then filtered under pressure and tanked and aged.
The different grades of varnish depend upon the treatment of the oil,
the proportion of oil and turpentine, the qualities of the gums, the
aging, etc. Some by rubbing give a very high polish, some give a
dull waxy finish, some are for out-of-door use, as Spar varnish and
carriage varnish, some are for floors, some for furniture, some are
high priced, some are cheap.

Process of Varnishing. The preliminary processes are the same as those
for applying shellac, i. e., the surface of the wood must be perfectly
even and smooth, and the staining, filling, and drying complete. Quick
drying varnishes, like shellac, are applied, with but little on
the brush. The heavy, high lustre varnishes, on the other hand, are
applied with the brush full so that the varnish may even drip off
the work. Then proceed as follows: Wipe off from the work the extra
varnish with the brush and clean the brush on the edge of the
cup. Repeat till the varnish is flowed over the work evenly. Be
particularly careful, in that respect, of edges and corners. Set to
dry in a dustless place. When dry and hard repeat the process from
three to six times. Each coat must dry thoroly before the next coat is
applied.

Varnish polishing consists in rubbing off the varnish, not in rubbing
it on, as in French polishing. To polish varnish, rub with a felt
pad, powdered pumice-stone and water. Rub till the surface is smooth,
unpitted and even, being careful not to rub