Yellow poplar (Liriodendron tglipifera) is found chiefly in West Virginia, Tennessee, Ken tucky and scatteringly through the Southern States. It is one of the softest of the hard woods, readily worked and finds its most im portant outlets to market in the production of millwork, boxes and crating, furniture and vehicles. It was at one time the most impcirtant material used in the production of automobile bodies but was largely displaced by the de velopment of satisfactory metal bodies.
Among the other hardwoods of chief im portance are included the elms, the chief species of which are the white elm (Ulmus americana) and the rock elm (Litmus racemosa) which is also known as cork elm. The most important uses of elm lumber are in the manufacture of boxes and crating and in furniture of the cheaper varieties. Basswood (Tilia ameri cana), which has a very wide range of growth, produces a very soft lumber of straight grain that is used in the production of boxes, crating, millwork, wood novelties, trunks, etc. Tupelo aquatica) is found in the same as cypreSs and is used largely for boxes and crates. Cottonwood (Populus del toides) is another southern product that is used chiefly for box and crating purposes. Black walnut (Juglans nigra), once the most favored of American woods for furniture manufacture, has become comparatively scarce and is now manufactured chiefly from scattered woodlots. It is used in the production of fine furniture and in the making of gunstocks, for which it is preferred over all other woods.
Manufacture of Imported The manufacture of woods imported in the log has become an important annex to the hardwood branch of the lumber industry, the products of chief importance being mahogany and Circas sian walnut. Mahogany as it is known in the trade includes Swietenia mahogani, from Cen tral America and southern Mexico, and Khaya senegaknsts, from Africa. Though the latter is not a true mahogany botanically, it pos sesses characteristics that place it commercially on a par with the product from the American tropics. The chief uses of mahogany are for furniture and interior finish. Importers of ma hogany also bring into the United States a considerable quantity of Spanish cedar, the principal use of which is for cigar boxes. Cir
cassian walnut is a wood of very pronounced figure used principally for interior finish and furniture.
The Veneer The manufacture of wood veneers is an important subsidiary factor of the lumber industry. Veneers range from the extremely thin material used in the production of fine furniture, piano cases, etc., to the thick veneers used in producing baskets and light boxes. Thin veneers are produced by the log until it is very soft and slicing it. The heavier veneer stock is produced by sawing the log with a high-speed circular saw. Mahogany, Circassian and American wal nut are the most important of the woods used in making thin veneers of fine furniture and finely figured mahogany logs suitable for the production of veneers bring extremely high prices. S;nce furniture veneers are apt to be but one-thirty-second of an inch in thickness or even less and are usually sold by the square foot, a single log will produce enough stock to cover a very large amount of surface.
In some cases veneer mills are operated in connection with sawmill plants, but generally veneer manufacture is a separate enterprise.
Preservative Treatment of In the early period of the lumber industry's develop ment only those woods of most serviceable character were marketed, but with the expan sion of demand that has come in recent years, bringing with it the rapid extermination of the varieties that had first preference for com mercial purposes, it has become necessary to develop means of utilizing practically all woods that grow to commercial size. One of the prin cipal difficulties with some of the timbers that have appeared in the markets in recent years is their lack of durability. On this account, the development of processes of wood preserva tion by chemical treatment has become an im portant adjunct to the lumber industry, deriv ing a large part of its impetus from the desire of American railroads to get away from the expense of frequent renewal of cross-ties, poles and posts. It has been estimated that the average life of an untreated cross-tie is about seven years and that the same tie, properly preserved, will last 17 years.