Elements of agricultural chemistry, in a course of lectures for the Board of Agriculture / By Sir Humphry Davy.

  • Davy, Humphry, Sir, 1778-1829.
Date:
1813
Catalogue details

Licence: Public Domain Mark

Credit: Elements of agricultural chemistry, in a course of lectures for the Board of Agriculture / By Sir Humphry Davy. Source: Wellcome Collection.

    105/428 (page 79)
    c 79n of some other trees, particularly the Spanish chesnut, have lately come into use. The following table will give a general idea of the relative value of different species of barks. It is founded on the result of experiments made by myself. Table of Numbers exhibiting the quantity of Tannin afforded by 480lbs. of different Barks, which express nearly their relative values. ! lb. Average of entire hark of middle sized Oak, cut in spring, 29 . — of Spanish Chesnut, 21 — of Leicester Willow, large size. 33 of Elm, 13 — of Common Willow, large, - 11 • of Ash, 16 of Beech, 10 of Horse Chesnut, 9 ~ of Sycamore, 11 of Lombardy Poplar, 15 of Birch, 8 of Hazel, - 14 of Black Thorn, - « 16 — of Coppice Oak, 32 of Oak cut in autumn, - 21 of Larch, cut in autumn. 8 White interior cortical layers of Oak Bark 72 The quantity of the tanning principle in barks differs in dif- ferent seasons ; when the spring has been very cold the quantity is smallest. On an average, 4 or 5lbs. of good oak bark are re- quired to form lib. of leather. The inner cortical layers in all barks contain the largest quantity of tannin. Barks contain the greatest proportion of tannin at the time the buds begin to open— the smallest quantity in winter.