=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 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.