RESISTANCE OP CONIFERS TO CREOSOTE INJECTION. 7 



Common name. Botanical name. 



Western hemlock Tsuga heterophylla. 



White fir Abies grandis. 



Noble fir Abies nobilis. 



Douglas fir Pseudotsuga taxifolia. 



Sitka spruce Picea sitchensis. 



Engelmann spruce Picea engelmanni. 



White spruce Picea canadensis. 



Western larch Larix occidentalis. 



Tamarack Larix laricina. 



Lodgepole pine Pinus murrayana. 



Jack pine Pinus divaricata. 



Western yellow pine 1 Pinus ponderosa. 



Spruce pine Pinus glabra. 



Longleaf pine Pinus palustris. 



Shortleaf pine Pinus echinata. 



Loblolly pine Pinus twda. 



Three pieces of heartwood and three of sapwood 2 were prepared 

 from each species for the penetrance tests. These specimens were 

 each 2 by 4 by 25 inches and were surfaced on all sides. A hole 

 1 inch in diameter and 1 inch deep was bored in each piece at the 

 center of one of the 4 by 25 inch faces. The specimens were sea- 

 soned until air dry before testing, and only those free from checks 

 and other defects were selected. The oven-dry weight and moisture 

 content of each piece at the time of treatment were determined. 



The specimens for the impregnation tests were cut 2 by 2 by 12 

 inches. Seven pieces of heartwood and seven of sapwood from each 

 species were tested. Those used were free from defects. The pieces 

 were allowed to season until thoroughly air dry. Just before im- 

 pregnation they were placed in an oven and held at a temperature of 

 100° C. for 48 hours. This rendered them practically oven, dry and 

 eliminated the effect of moisture. 



METHOD OF APPLYING THE CREOSOTE. 



PENETRANCE TESTS. 



In the penetrance tests the specimens were subjected to creosote at 

 a pressure of 85 to 90 pounds per square inch, the maximum obtain- 

 able with the apparatus employed. The length of time required to 

 heat the apparatus made it necessary to carry on the tests at tempera- 



1 A tree from California and one from Montana were tested. 



2 In the case of yew, tamarack, and western larch the sapwood was so thin that no 

 sapwood specimens could be obtained. In the cases of Alpine fir, eastern hemlock, 

 western hemlock, white fir, noble fir, Sitka spruce, Engelmann spruce, and white spruce 

 there was no color distinction between sapwood and heartwood. Wood from the outer 

 2| inches of growth, however, was considered sapwood and that from the portion within 

 this area was considered heartwood. 



