BALSAM FIR. 



13 



RESIN CONTENTS. 



The complaints against the larger amount of pitch in balsam fir 

 are somewhat strange in view of the fact that the actual resin content 

 of balsam fir is less than that of spruce. Resin in coniferous wood 

 occurs normally in cells, of which the wood is built up as a house is 

 built of bricks, and in the spaces between the cells, known as resin 

 ducts, running vertically and horizontally through the wood. These 

 resin ducts may be seen on cross sections of freshly cut wood as 

 whiter or darker spots marked by exuded droplets of resin. On 

 radial and tangential sections the ducts appear as fine lines or dots 

 of different color. The difference in resin content of the different 

 genera and species of the conifers depends mainly upon the number 

 and size of their resin ducts. Balsam fir is one of the few conifers 

 that lack resin ducts entirely, a thing which serves readily to dis- 

 tinguish it from the spruces and pines. Resin is found in the wood 

 of balsam fir only in the interior of the cells, where it occurs in the 

 form of small droplets. The bark of balsam fir is very rich in resin, 

 but after the former is rossed off the wood should be freer of resin than 

 spruce, which contains resin ducts and resin cells. Therefore the 

 pitch, which according to all reports is the greatest drawback to 

 balsam pulpwood, must either come from the resin in bark left on the 

 surface of the block or else is formed in the process of grinding, in 

 which case it is not of a resinous nature. In either event, the presence 

 of pitch is apparently not due to any properl y of the wood itself. 



A chemical determination of the resin contents of six spruce and of 

 four balsam-fir sections made by the Bureau of Chemistry, United 

 States Department of Agriculture, in 1904, gave the following 



results : 



Table 3. — Bcsin contents of spruce and balsam fir. 



SPRUCE. 





Moisture. 



Non- 

 volatile 

 resins. 



Volatile 

 resins. 



Total 

 amount 



of 

 resins. 



Top 



Per cent. 

 5.60 

 5.66 

 6.39 

 5.85 

 5.57 

 5.62 



Per cent. 

 0.88 

 .92 

 .76 

 1.36 

 2.33 

 1.48 



Per cent. 

 0.23 



.67 



.49 

 .27 

 .50 

 .34 



Per cent. 

 1.11 



Middle section 



1.59 



Butt section 



1.25 



Top 



1.63 



Middle section . . . 



2.83 



Butt section 



1.82 







Total 









10.23 



Average 









1.70 













BALSAM FIR. 



Butt section 



5.31 

 5.06 

 5.01 

 4.80 



1.23 



.58 

 .77 

 .67 



0.19 

 .15 

 .19 



.48 



1.42 



Middle section 



.73 



Butt section 



.96 



Middle section . 



1.15 







Total 









4.26 



Average '. 









1.06 













