_Resin_ is the substance remaining after the crude turpentine has been distilled. It is used in the manufacture of varnish, sealing-wax, and soap. Finely powdered resin is also mixed with wood-pulp in the manufacture of wrapping-paper. It gives the latter a glazed surface and renders it almost water-proof. Most of the world's product of resin comes from the turpentine district of the United States, and about four-fifths of it is exported to Europe. When resin is subjected to distillation at a still higher temperature, _resin oil_, a very heavy turpentine, is given off, and a viscous substance known as _pitch_ remains. A considerable amount of this is still made in the United States, but the greater part comes from the pine-forests of Russia and Scandinavia. When pine-wood is distilled, _tar_ is the chief product. In Russia tar is generally made by burning green logs covered with turf, over a pit. _Creosote_, or wood preservative, is made from tar. The various pine-tree products, creosote excepted, are commonly known as "naval stores," the tar being used in water-proofing the rigging of vessels, the pitch in calking the seams in between planks, in the decks and hulls. =Other Resins and Gums Used in the Arts.=--Most of the gums and resins used in the arts and sciences are the hardened sap of plants--in some cases exuding by natural means from the bark, in others resulting from the puncture of the bark. The _lac_ of commerce is due to the puncture of the young branches of a tree, frequently a fig (_Ficus religiosa_) growing in the tropical forests of India. The hardened sap incrusts twigs forming _stick-lac_; when crushed, washed, and freed from the woody matter it is _seed-lac_; when melted and cooled in flakes it is _shell-lac_, the form best known in commerce. It is the chief ingredient in sealing-wax, and is extensively used as a varnish. It is also used in fireworks on account of its inflammability. _Dammar_ is the product of a tree growing in the East Indies; it is the basis of a very fine white varnish. _Copal_ is a term applied to oleo-resins soluble in turpentine, and used almost universally as varnishes. They come from the tropical regions of South America, Africa, and from the East Indies. _Kauri_ is the fossil gum of a cone-bearing tree dug from the ground in northern New Zealand. _Amber_ is the fossil gum of extinct cone-bearing trees found mainly along the Baltic coast of Prussia. It is used chiefly for the mouth-pieces of tobacco-pipes and cigar-holders; the inferior product is made into varnish. It is sold wherever tobacco is used. _Sandarach_, found on the north African coast, is used principally in Europe, being employed as a varnish. The United States and Great Britain consume most of the foregoing products. QUESTIONS FOR DISCUSSION Name any elastic substance you know about that is in every way a substitute for rubber. What has been the relation between rubber and good roads? Describe the structure of a bicycle tire.