8 BULLETIN" 606, U. S. DEPARTMENT OF AGBICTJLTUEE. 



the time was recorded at which the preservative first penetrated 

 a surface. The periods of treatment were one-half hoar, 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 irhich treatments 



irere made. 



Run No. 



Pressure. 



Pressure 

 period. 



Tempera- 

 ture of 

 preserva- 

 tive. 



1 



Pounds per 

 square inch.. 

 Atmospheric. 

 25 

 50 

 75 

 100 

 125 

 150 



Hours. 

 1 

 1 

 1 

 1 

 1 

 1 

 1 



"F. 



180-185 



2 



180-185 



3 



180-185 



4 



180-185 



5 



180-185 



6 



180-185 



7 



180-185 









