8 



BULLETIN 101, U. S. DEPARTMENT OF AGRICULTURE. 



tures between 120° and 160° F. Readings of temperature and pres- 

 sure were made every 10 minutes. 



The specimens were removed after definite periods and the time 

 noted when oil first penetrated a surface. Three periods were taken, 

 one-half hour, one hour, and two hours. One of each set of three 

 specimens was treated for each of these periods. The measured pene- 

 trations of the various species are, therefore, directly comparable with 

 each other. 



The wood of some of the specimens was completely penetrated 

 within a few seconds. This was true of the sap wood of some of the 

 pines and, in a few cases, of the heartwood also. When this occurred, 

 the pieces were removed as soon as penetrated, instead of at the end 

 of the period. 



The treated pieces were sawed transversely and longitudinally along 

 the center lines (PI. IV, fig. 1) and the sawed surfaces immediately 

 coated with collodion to prevent the creosote from staining the un- 

 treated surface. The maximum penetration of oil in longitudinal, 

 tangential, and radial directions was measured to the nearest 0.01 

 inch and the average penetration in each direction estimated as 

 closely as possible. Each specimen was photographed. 



IMPREGNATION TESTS. 



The specimens prepared for impregnation tests were separated into 

 seven series, with one heartwood and one sapwood piece of each spe- 

 cies in a series. Seven runs were made, in which all conditions of 

 treatment except pressure were maintained as nearly uniform as pos- 

 sible. The conditions of treatment are given in Table 1. 



Table 1. — Conditions of treatment in impregnation cylinder. 



Run 

 number. 



Pressure. 



Time of 

 pressure. 



Temperature 

 of pre- 

 servative. 



1 

 2 

 3 

 4 

 5 

 6 

 7 



Lbs. per sq. in. 

 25 

 50 

 75 

 100 

 125 

 150 

 Atmospheric. 



Hours. 



°F. 

 175 to 1S5 

 175 to 185 

 175 to 185 

 175 to 185 

 175 to 185 

 175 to 185 

 175 to 185 



All pieces were weighed before treatment, also within 1 hour 

 after treatment, and again after 48 hours. The weights taken after 

 48 hours are the ones used in this report. 



