654 UTILIZATION OF BARK AND ITS CONSTITUENTS. 



5. Measures for Bark. 



In selling bark-coppice by area, it is important to know how 

 to estimate the quantity of bark that has been harvested. 

 This may be done by measuring its rough volume ; by weight ; 

 or indirectly, by measuring the volume of the barked wood, 

 from which the yield of bark may be determined by means of 

 experimental ratios. 



Measurement by rough volume is done by the bale. 

 Although this method has the advantage, that the bark can 

 be removed as soon as it is sufficiently dry, and there is thus 

 little danger of any loss of tannin, yet it affords for both 

 purchaser and seller such an uncertain measure of the yield, 

 that it is employed only to a limited extent. If measurements 

 are to be made by bales, not only the length and girth of the 

 bales must be nearly uniform, but also the bark must be packed 

 uniformly in each bale. 



The best, and at present, the most usual sale-measurement 

 is the weight. As soon as the bark is dry it is packed in bales 

 and weighed in the forest by means of a steel-yard or spring- 

 balance. Everything then depends on the degree of dryness 

 of the bark, for green bark must lose 40 to 50 per cent, of 

 water to become air-dry. In the interest of the purchaser, 

 however, the bark must not be kept in the forest a day longer 

 than is necessary, owing to the danger of a loss of tannin. 

 Although one might anticipate disputes between seller and 

 purchaser as to the proper date for measuring bark, yet 

 experience proves that this seldom happens. A prudent 

 tanner will allow the bark to remain in the forest no longer 

 than is absolutely necessary ; he knows that it is more to his 

 interest to pay for the bark when somewhat moist than to risk 

 its being washed badly by rain. 



The third mode of measuring bark consists in measuring 

 the peeled wood, and assuming that its volume will bear a 

 fixed ratio to that of the bark which has been harvested. This 

 custom is followed always in Franconia. It cannot be denies 

 that this method has certain advantages, as it saves labour 

 and avoids inconvenience, but to it is attached the great 

 disadvantage that the ratio between wood and bark varied 



