32 BULLETIN 101, U. S. DEPARTMENT OF AGRICULTURE. 



The average oven-dry weight per cubic foot of seven heart specimens was 

 32.2 pounds, and of six sap specimens 26 pounds. 



Two heartwood pieces of spruce pine (Nos. 225 and 240) treated like the sap- 

 wood. These pieces became saturated with oil almost as soon as pressure was 

 applied, and on splitting both springwood and summerwood were found to be 

 uniformly discolored with creosote. Examined microscopically, no difference 

 appeared between these pieces and other heartwood directly adjacent that was 

 very resistant to penetration. 



Three heartwood pieces were found, however, that resisted penetration in 

 the manner usually noted in the heartwood of pine. These pieces of spruce 

 pine were, in fact, among the most impenetrable in the entire series of species 

 tested. They were penetrated in the summerwood somewhat more quickly 

 than in the springwood, and microscopic examination showed that the sum- 

 merwood plainly was the most heavily treated portion. The medullary rays 

 were frequently lightly treated. While radial and longitudinal ducts were often 

 filled with what appeared to be a mixture of resin and creosote, they did not 

 seem to aid materially in the penetration. The presence of a bright yellow 

 substance in many of the tracheids of the heartwood, especially near resin ducts 

 and in the springwood. seemed to indicate that resin had been forced from the 

 ducts into the surrounding tracheids. 



In the sapwood. while the summerwood treated more easily than the spring- 

 wood, yet the latter was also very penetrable. Microscopic examination showed 

 the summerwood to be saturated with oil and the springwood deeply colored. 

 The medullary rays were usually treated. The resin ducts of the sapwood 

 were usually heavily treated and seemed to be responsible for the quick pene- 

 trance of sapwood. 



In the cylinder the heartwood piece treated in the nonpressure run showed 

 that the greatest penetrance took place in the summerwood resin ducts. The 

 springwood was treated for I to 1 inch, while summerwood was treated 

 (around resin ducts only) from 1 to 6 inches. In some of the pressure treat- 

 ments the springwood also was found to be heavily treated. The absorption, 

 as indicated by the color of the treated sticks was very uneven. 



The sapwood was very heavily treated in both springwood and summerwood; 

 the latter, however, seemed to have taken the oil more quickly. Increasing the 

 pressure did not seem to greatly increase the absorption in the sapwood, be- 

 cause it could be saturated without pressure. In general, spruce pine was 

 extremely erratic in its penetrability and in its absorption of creosote. Some 

 portions of heartwood were completely saturated with oil. while others di- 

 rectly adjacent were almost impenetrable. The average longitudinal penetra- 

 tion in heartwood was about 5 times the average radial and 16 times the average 

 tangential penetrations. 



LOXGLEAF PINE (PINUS PALUSTRIS). 



The growth rings of longleaf pine were usually narrow, with very dense sum- 

 merwood. Resin cells were never present. Resin passages were numerous and 

 large, chiefly in the summerwood, and contained tyloses. Ray ducts were few. 



The average oven-dry weight in pounds per cubic foot of six heart specimens 

 was 35.3 pounds, and of six sap specimens 22.8 pounds. 1 



In the heartwood while the summerwood was more penetrable than the 

 springwood the latter was also easily treated. Both longitudinal and ray 



1 It should be noted that the dry weight of the sapwood was only two-thirds that of 

 the heartwood. This was due to much thinner summerwood bands in the sapwood. 



