500 BARK. 



supported on stakes driven crosswise into the {:!;round (fig. 276). 

 In tliis case it is necessary to place the rolls of bark so that they 

 overlap one another, and with the outside uppermost. The 

 looser they are placed, and the fewer pieces there are on a trestle, 

 the quicker the}' dry. This is undoubtedly a good method of 

 drying bark, as it nowhere touches the ground. 



"Whenever the bark is allowed to form rolls, the drying process 

 is very simple, for the rolls are generally removed as soon as 

 they are prepared, and left to dry in well-ventilated sheds. If 

 the rolls of bark are not removed till the end of the felling, they 

 should be piled in pyramids of five to ten on the felling-area. 

 The rolls should be loosely tied together so as to admit the air, 

 but the middle of the rolls, enlaced by the withes, frequently 

 becomes mouldy. 



"When standing stems arc peeled, drying the bark does not 

 give any trouble; the strips of bark remain hanging on the 

 trees, and roll-up to such a degree in drying that the inner 

 surface of the bast is thoroughly protected against rain. The 

 loose pieces are hung-up to dry on the top of the stems. 



The degree of dryness attained may evidently vary consider- 

 ably. Practically, however, besides the green "bark, freshly 

 stripped from the tree, traders distinguish air-dried from meal- 

 dried bark. Bark is said to be air-dried when, on bending, it 

 breaks easily ; meal-dried, when it has lost all flexibility and 

 becomes brittle. According to Baur, bark, in passing from the 

 green to the air-dried condition, loses considerably in weight ; 

 from 32 to 49 %, according to quality, that from the branches 

 losing most weight, and coarser stem-bark the least. The loss in 

 weight, therefore, increases with the age of the wood, i.e., from 

 the foot of a shoot to its top. In a similar way shrinkage of 

 volume takes place, from 21 to 41 %, according to the part from 

 which the bark is taken. 



In passing from the air-dried to the meal-dried condition, the 

 bark loses in weight only 4 to 5 °/o, whilst it shrinks in volume 

 11 to 20%. Schuberg found a loss of weight of 35 % for bark 

 passing from the green to the air-dried condition, and a further 

 loss of 14°/ in becoming meal-dried. 



