50 THE WESTERN HEMLOCK. 



the cord, and assuming an average percentage of 10 for Eastern and 16 

 for Western bark, the quantity of tannin in each would be as follows: 



Table 20. — Yield of tannin per cord of Western and Eastern bark. 



Pounds. 



Washington bark 358. 4 



Eastern bark 224. 



Difference 134. 4 



VOLUME AND YIELD. 



Although the cord is used as a standard of measure for bark, it is 

 usually sold by weight, in order to avoid variation due to loose piling. 

 Throughout the East 2,240 pounds are usually called a cord, although 

 in some places 2,000 pounds are accepted. It was impossible to secure 

 any yield tables based on actual practice in the regions covered by this 

 report; therefore the thickness of bark at various heights was meas- 

 ured on all trees scaled, and the amount in cubic feet produced by the 

 average tree of given diameter, and also by the acre, was computed. 

 These figures were then converted into long and short cords on a basis 

 of 66.6 cubic feet to 2,000 pounds and 77 cubic feet to 2.240 pounds. 

 This was done separately for mature and second-growth timber, assum- 

 ing that in the latter only the merchantable log length would be peeled, 

 and that in the former all bark would be taken from the stump to a 

 point where the tree is 12 inches in diameter. The following table 

 gives, on a basis of diameter breasthigh, the volume of bark and the 

 number of trees required to make a cord of 2,000 pounds and of 2,210 

 pounds. 



Table 21 . — Volume of bark per tree and trees per cord. 



