8 
BULLETIN 606, U. S. DEPARTMENT OF AGRICULTURE. 
the time was recorded at which the preservative first penetrated 
a surface. The periods of treatment were one-half hour, one hour, 
and two hours, respectively, for the three pieces from each species. 
After treatment the specimens were sawed longitudinally and 
transversely along the center lines. (Fig. 2.) Immediately after 
sawing, the fresh surface was painted with water glass (sodium 
silicate solution) to prevent the creosote from staining the untreated 
surface. The longitudinal penetrations were measured on the sur- 
face obtained by sawing the specimens through the longitudinal 
center line. The average was obtained by measuring the area of the 
treated zone on this surface and dividing by the width of the pene- 
tration, The maximum and average radial and tangential penetra- 
Fig. 2. — The general shape of the test pieces treated in the penetrance apparatus. 
tions were measured with a steel scale on the surface obtained by 
sawing the specimens transversely through the center line. These 
lines are indicated in figure 2 ; and Plates V to XII show specimens 
after being sawed. Radial and longitudinal penetrations were 
measured to the nearest 0.01 inch. 
Photographs were taken of each specimen after treatment. 
IMPREGNATION TESTS. 
The impregnation tests comprised a series of seven treatments in 
which the pressure was varied and other conditions kept as nearly 
constant as possible. Each treatment was made on a heartwood 
specimen from each species. A sapwood specimen was also included 
from species having both sapwood and heartwood available. 
The conditions of treatment are shown in Table 1. 
Table 1. — The pressure, period, and temperature at which treatments 
v:erc made. 
Hun No. 
Pressure. 
j Pounds per 
square inch. 
1 Umospheric. 
2 25 
3 1 50 
4 75 
5 100 
6 125 
7 150 
Tempera- 
ture of 
preserva- 
tive. 
°F. 
180-185 
180-185 
1S0-1S5 
180-185 
180-185 
180-185 
180-185 
