650 UTILIZATION OF BARK AND ITS CONSTITUENTS. 



pieces there are on a trestle, the quicker they 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 generally the rolls are 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 tied loosely together so 

 as to admit the air, but the middle of the rolls, enlaced by 

 the withes, frequently becomes mouldy. 



When standing shoots are 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. 



Evidently the degree of dryness attained may vary con- 

 siderably. Practically, 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 become 

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

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

 from 32 to 49 per cent., 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 per cent., 

 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 per cent., whilst it shrinks 

 in volume 11 to 20 per cent. Schuberg found a loss of weight 

 of 35 per cent, for bark passing from the green to the 

 air-dried condition, and a further loss of 14 per cent, in 

 becoming meal-dried. 



3. Assortments of Bark and formation of Hale-Lots. 



In estimating the yield of bark, greater care than is usually 

 bestowed should be given to the business of assorting the bark 



