TANNING. 



getables which are of an astringent nature, contain 

 tannin (which may be known by their giving preci- 

 pitates with gelatine, insoluble in water), and will 

 answer this purpose. The leaves, branches, fruit, 

 flowers, of a vast number of plants ; every part of the 

 oak, as the leaves and acorns, oak saw-dust, and the 

 barks of almost all trees, contain more or less tannin. 

 Mr. Biggins made a great many experiments 

 upon the quantity of tanning principle in various 

 barks, from which he constructed the following 

 table. 



Tanning principle (in grains), 



i from half a pint of infusion 



and an ounce of solution of 

 glue. u 



Bark of elm, 28 

 oak, cut in winter, - 30 

 horse-chesnut, 30 

 beech, 31 

 willow (boughs) 31 

 elder, - 41 

 plum-tree, 58 

 willow (trunk), - 52 

 sycamore, - 53 

 birch, 54 

 cherry-tree, 59 

 sallow, - - 59 

 mountain-ash, 60 

 poplar, 76 

 hazel, - 79 

 ash, - - 82 

 Spanish chesnut, - 98 

 smooth oak, - - 104 

 oak, cut in spring, 108 

 Huntingdon, or Leices- 

 tershire willow, - 109 

 sumach, - - 158 



