

PLANTING, 75 



former. Trees whose bark is valuable require to be felled before the 

 complete expansion of the leaf. From the middle of April to the end of 

 June is the proper time for the oak; the larch should be peeled earlier. 

 The birch having a tough outer cuticle of no use to the tanner, and as 

 this is more easily separated from the proper bark after the sap has par- 

 tially circulated in the leaves, it is generally left standing until the other 

 species of trees are felled and barked. 



The process of barking is, in general, well understood. The harvesting 

 of the bark is of the greatest importance, for if it be suffered to heat or 

 ferment, it loses its colour, becomes mouldy and of little value. The 

 best mode is to make what the foresters term temporary lofts of about two 

 feet in width, and of a length sufficient to hold a day's peeling of bark. 

 These lofts are formed by driving forked stakes into the ground for 

 bearers, about three feet in height in the back row, and two and a half feet 

 in the front; a sloping floor is then constructed by laying loppings between 

 the forks of the bearers. The bark is then placed on the sloping floor 

 with the thick ends towards the top or higher side, the smaller bark is laid 

 on to the depth of six or ten inches, and the broad pieces placed over the 

 whole as a covering to carry off the wet, should rain happen before the 

 bark is sufficiently dry to be stacked. In three or four days it should be 

 turned to prevent heating or moulding, and in ten days, more or less, it 

 will be sufficiently dry to be stacked until wanted for the tanner. In order 

 to prevent fermenting when stacked, the width of the pile should not 

 exceed eight feet. The roof should be formed and thatched as a corn or 

 hay stack. In preparing the bark when ready for the tanner, it is cut into 

 pieces about three inches in length, and weighed. It is sold by weight. 



The quantity of tannin contained in the bark of different forest-trees has 

 been ascertained by Sir Humphry Davy, and although the proportion of 

 tannin afforded by the bark varies according as the spring may be 

 favourable in temperature, the following numbers will be found to express 

 nearly their relative values, if the larch cut in autumn be excepted : 

 Average of entire bark of middle-sized oak, cut in spring 29 



of Spanish chestnut . . 21 



of Leicester willow, large size . ' 33 



ofelm ... . 13 



of common willow, large . 11 



of ash . 16 



of beech ... 10 



of horse-chestnut . . 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* 



In general the bark of the larch is not worth more than half the price of 

 oak bark, and the proportion given to larch in the above table may, there- 

 fore, be considered too small. The great disproportion between the pro- 

 duce of tannin afforded by the inner bark and that of outer layers, shews 

 with what care the harvesting of the bark should be performed to prevent 



* Agricultural Chemistry, p. 79. 



