—The American walnut grows wild over a very large portion of the country, especially the middle section west of Maryland to the Mississippi river. The walnut tree is especially abundant along the Ohio river, where it forms in the early summer a dense foliage. The trees often attain a very great size, reaching a diameter as great as five feet.
The walnut trees grow only on rich soil, hence, unless the country was very hilly and unsuitable for cultivation, the walnut forests were the first to fall before the axe of the pioneer. Later the demand for walnut lumber completed the devastation of the walnut forests, until now very often in the regions where fifty years ago the trees were extremely abundant a large walnut tree is rarely seen. The walnut lumber has peculiar lasting powers, and on account of its natural color and grain is of the highest value for building and ornamental purposes. The early farmers in the Ohio valley made their rail fences out of walnut trees. The wild nut grows in a dense kernel and is covered with a thick pericarp which is green even at the time when the fruit is ripe. After a frost when the fruit naturally falls from the trees the outer covering disintegrates. When the nuts are gathered by boys the outer covering is usually beaten off with clubs. It contains a coloring matter of a brown or brownish-black tint which the early housewives used for dyeing homespun cloth. The bark of the tree also contains to a greater or less extent the same coloring matter. The kernel of the walnut, that is, the edible portion, is extremely rich in oil and protein and has a very pleasant taste. Like other nuts the walnut is best during its first winter, since on longer keeping the oil tends to become rancid and the fruit unpalatable.
White Walnut (Juglans regia L.).
—The white walnut, commonly known as the English walnut, is grown very extensively in France. All the departments of south central and southeastern France grow these walnuts as a valued crop. The best walnut orchards are at an altitude of from 600 to 900 feet. Only the outer or exposed limbs produce perfect nuts. In planting the most important precaution is to give the trees plenty of room, 15 yards is about the usual distance at which they are planted. The trees are cultivated and fertilized with manure and commercial fertilizers every two or three years. A bearing orchard of these white walnuts in France is worth from four to five hundred dollars per acre and may yield a revenue of from seventy-five to one hundred dollars a year per acre. The nuts ripen from the middle of September to the end of October. These nuts are used largely in America as a food, for which purpose the kernels are carefully extracted in halves, commonly known as “walnut halves.” In France an excellent table oil is expressed from the dry nut which for many culinary purposes is valued as highly as olive oil. After extraction the oil cake is used for stock food. The white walnut is supposed to have been originally introduced from Persia, though it is commonly known as the English walnut. In the United States the butternut tree is commonly known as the white walnut.
The composition of the kernel of the dry walnut is shown by the following data:
Edible portion:
| Water, | 2.5 | percent |
| Protein, | 16.6 | „ |
| Fat, | 63.4 | „ |
| Total carbohydrates, | 16.1 | „ |
| Ash, | 1.4 | „ |
As purchased:
| Refuse, | 58.1 | percent |
| Water, | 1.0 | „ |
| Protein, | 7.0 | „ |
| Fat, | 26.6 | „ |
| Total carbohydrates, | 6.7 | „ |
| Ash, | .6 | „ |