12 
average of three specimens of each species treated in the penetrance 
apparatus, and the absorptions are the average of seven specimens 
treated in the cylinder. However, a close relation between penetra- 
tion and absorption could not be expected in many of the species, 
For example, species such as red oak and chestnut oak have large 
open pores or vessels which allow the preservative to pass easily 
from one end of the stick to the other. The wood prosenchyma of 
these species is very difficult to penetrate and treatment results 
mainly in coating the vessel wails with the preservative and not in 
AVERAGE AgSORPTIOM 
A L8S.P2RCU.FT. 
BLACK WILLOW 
LARGE TOOTH ASPEN 
WHITE ELM 
GREEK ASH 
SLIPPERY ELM 
SILVER 8APLE 
SWEET BIRCH 
REDGUM 
WHITE ASH- 
SILVER MAPLE 
EASSWOOD 
TUPELO GUM 
WILD RED CHERRV 
TUPELO GUM- 
mTTI i T ,"T. i ? T 
Tir/'I-::. 
Fig. 3. — Comparative absorptions and penetrations. 
a complete impregnation of the wood substance. Slippery elm has 
large open vessels similar to those of red oak and chestnut oak, but 
in this case the wood prosenchyma readily absorbs the preservative. 
It was therefore possible to secure both a complete penetration and a 
fairly heavy absorption in this wood. In hickory, the large vessels 
are almost completely closed by tyloses, but a fairly good penetration 
was obtained on account of the comparative ease with which the wood 
prosenchyma absorbed creosote. Species in which the tyloses are 
more or less irregularly distributed, such as black willow and large- 
