Elements of practical agriculture; comprehending the cultivation of plants, the husbandry of the domestic animals, and the economy of the farm / By David Low.

  • Low, David, 1786-1859.
Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: Elements of practical agriculture; comprehending the cultivation of plants, the husbandry of the domestic animals, and the economy of the farm / By David Low. Source: Wellcome Collection.

    491/842 (page 467)
    Of these forest-trees the oak is the most esteemed for its tan¬ nin, although it appears that certain species of willow are not in¬ ferior to it in the quantity and quality of the tannin which they produce. The oak produces tannin from its galls, but it is chiefly pro¬ duced from its bark, and this in the largest quantity when the buds begin to open in spring. It yields the smallest quantity in winter, after the autumnal descent of the sap. It is for this reason that the oak is too frequently cut down at a time which, though favourable for the production of tannin, is not so for the ultimate durability of the timber. Sir Humphrey Davy made various experiments on the quantity of tannin yielded by the bark of different species of trees. He found that the greatest quantity was produced by the Leicester willow of large size. From 480 lb. of bark, The Large-sized Willow yielded ... 33 lb. The Common Willow, . . . . 11 Coppice Oak, . • • - 32 Middle-sized Oak cut in spring, . . . 29 The Spanish Chestnut cut in autumn > . . 21 The Ash, . . . . . .16 The Black Thorn, . . . . .16 The Larch, when cut in autumn, ... 8 Of these trees, the larch, it will appear, yields the smallest quantity, weight for weight; but then the larch produces a considerable quantity of bark, for which reason it is common to strip the trees of their bark when felled. Other coniferous trees are rich in the tannin principle, as the Hemlock-spruce of America. The Myrtle family of plants are some of them very productive of tannin. The loftiest timber trees of New Holland and Van Diemen’s Land are of this family, and tannin in considerable quantity has been recently obtained from the Australian woods. From the same vast country Acacia has been imported on account of its tannin ; for it is to be observed that several of this genus yield tannin in great quantity. In some species of Acacia of the