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gum and copal

VARNISH. The chief ingredient of the best varnish is gum copal, a substance exuded from the copal tree, which is found in Mexico, Africa, Brazil, New Zealand, India and the East Indies. The East Indies and New Zealand are the principal sources of the United States supply. It resembles amber—which is superior to it, but is too expensive for use in ordinary commercial varnishes.

An interesting fact is that the fresh gum is not the high-grade gum copal of com merce—it is, on the contrary, rated as decidedly inferior. The most highly con sidered is the fossilized gum that exuded from trees a thousand years or more ago and has since remained buried in the earth. It is found by probing the soil with sharp pointed instruments made for the purpose. Its price ranges from $200 a ton up, and the annual importations from ten to thirteen thousand tons. It is said that the ship ments from New Zealand during the last quarter of a century have amounted to more than the trees now growing there could supply in ten thousand years.

Linseed oil and turpentine are, after gum copal, the principal varnish components. To unite these elements requires elaborate apparatus to melt the copal gum, and great skill in the entire manufacture..

Other varnishes are made by combining various gums or resins, as cowrie, or "kauri," and dammar, or their combinations with oil, in any one of a number of sol vents—alcohol (both grain and wood), benzine, carbon bisulphide, etc. Among the coloring agents used are annatto, indigo and saffron.

Varnishes are variously classified, (1) by the gum component, (2) by the solvent, (3) by the chief uses. "Spirit" varnishes are those which are quick drying.