The trunk’s value increases with age. The dark colored heartwood only is merchantable, and young trees have little heartwood. The thick, white sap constitutes most of the trunk until long after the tree has reached small sawlog size. Then the transformation to the dark, valuable heartwood goes on with fair rapidity, and the outer shell of sapwood becomes thinner as the heart increases, and in time a trunk is produced which is fit for good logs. Value comes only with age. The quarter or half a century which has passed since the country was so diligently ransacked for merchantable walnut, has been sufficient to develop many a tree which was then rejected by the purchasers. Many a tree now a foot in diameter had scarcely sprouted then. In a region of 700,000 square miles, walnut trees do not need to grow very close together to produce a yearly cut of 30,000,000 or 40,000,000 feet. Black walnut is valuable for its color, figure, and the fine polish it takes. It is stronger than white oak, weight for weight, but it is eight pounds lighter per cubic foot. The figure of the wood is due wholly to the annual rings, as its medullary rays are invisible to the naked eye. The wood is very porous, and the pores are diffused in all parts of the annual rings, except in the thin, pencil-like mark representing the outward boundary of the summerwood. When sapwood changes to heartwood, some of the pores disappear, but those which remain are abundantly sufficient to absorb any stains or fillers which the wood finisher may wish to apply. The annual sawmill cut of black walnut in the United States is from 35,000,000 to 40,000,000 feet, but much goes to foreign countries in the log, and a considerable quantity goes to veneer mills--about 2,500,000 feet a year--and a quantity finds its way to various factories where it is worked up without any statistical record being made of it. Black walnut is never used as rough lumber. It all goes to factories of some kind to be converted into finished commodities. It is not possible to say where it all goes, for statistics of manufacture are fragmentary in this country. It may be of interest to know that demand for walnut by factories in the following states was 11,641,137 feet in 1910: Alabama, Arkansas, Illinois, Kentucky, Maryland, Massachusetts, Missouri, North Carolina, and Texas. The wood served so many purposes that a list of them would be monotonous. In Illinois the largest users are the sewing machine and the musical instrument industries; in Michigan the makers of automobiles and of musical instruments; in Kentucky the manufacturers of coffins, furniture, and musical instruments; in Massachusetts, the makers of furniture and of firearms. These uses probably afford a fairly accurate index for the whole country. During the Civil war the largest demand for walnut came from gunstock makers. Doubtless the largest use from 1865 to 1885 was for furniture.