60(5 Forestry Quarterly 



and tangential penetration could usually be disregarded. Where no 

 radial ducts were present, radial and tangential penetrations could 

 be considered as equal, and they were found to be between one- 

 twentieth and one one-hundred-twentieth of the longitudinal 

 penetrations. 



"2. Absorption curves platted for the specimens treated in the 

 cylinder show that those species which were most difficult to 

 impregnate gave the most uniform absorption results, and that 

 the sapwood of those species containing resin ducts gave the most 

 erratic absorption results. They also showed that the sapwood 

 of pines, as distinguished by its color from heartwood, was not 

 always easier to treat than the heartwood. The color line in the 

 wood does not necessarily separate the easily treated wood from 

 the portions treated with difficulty. Some sapwood treated like 

 heartwood and some heartwood treated like sapwood; all of these 

 conditions are possible in the same cross section of a tree. As a 

 consequence of this, the absorption curves for pines were, as a 

 rule, very erratic, especially the sapwood curves. 



"3. The resiilts obtained with a given species of wood can not 

 always be applied to another species, however similar in structure 

 the two may appear to be. This fact is strikingly evident in the 

 treatment of heartwood larch and tamarack. Even woods of 

 the same species show variations when grown under widely different 

 conditions, as, for example, Western Yellow pine from California 

 and from Montana." 



An attempt is made to group with respect to treatment the 

 woods of the twenty species of conifers tested, but the proposed 

 classifications are based too much on empirical data to be wholly 

 satisfactory. The following species may be successfully treated 

 in the round form: Engelmann spruce, Douglas fir, tamarack, 

 Western larch, and all of the pines. Those considered unadapted 

 to treatment in the form of round timbers include the Alpine, 

 Noble and White firs, Eastern and Western hemlock. Redwood, 

 Sitka spruce, and yew. 



S. J. R. 



