BULLETIN 286, TJ. S. DEPABTMENT OF AGRICULTURE. 
LONGLEAF PINE. 
Steamed for 6 hours at 30 pounds pressure; vacuum of 26 inches applied for 1 hour; 
cylinder filled with creosote and pressure of 128 pounds applied for 5 J hours at a 
temperature of 140° F. Absorption, 12| pounds per cubic foot of wood. 
DOUGLAS PIR. 1 
Boiling process. — Boiled in creosote for 21J hours at temperature of 215° F.; 2 loss of 
moisture during boiling, 1.2 pounds per cubic foot of wood; pressure raised from to 
145 pounds per square inch in 5f hours; temperature about 190° F. Absorption of 
oil, 11.2 pounds per cubic foot of wood, as determined by measuring tank readings. 
Steaming process. — Steamed at 90 pounds pressure per square inch for 4J hours; 
temperature about 325° F.; vacuum of 20 inches applied for 18J hours; temperature 
220° F. at end of period; cylinder filled with oil and pressure raised from to maximum 
pressure of 140 pounds per square inch; pressure period, 24; hours; temperature of the 
oil, about 208° F. Absorption, 3.1 pounds per cubic foot of wood, as figured from 
increase in original weight of stringers. The stringers were not weighed after steam- 
ing, so that the probable loss can not be taken into account in computing the absorption. 
METHOD OF TESTING. 
The stringers were tested in bending by supporting them at the 
ends and applying the load at two points located one-third of the 
span from each of the end supports. This system corresponds 
closely to conditions of practice. In testing the beams the load was 
applied gradually and a record kept of the deflections corresponding 
to regular load increments. Four factors were calculated from the 
data derived from each bending test, all in terms of pounds per 
square inch: 
FIBER STRESS AT ELASTIC LIMIT. 
This is the greatest stress that can occur in a beam loaded with 
►an external load from which it will recover without permanent 
deflection. 
MODULUS OF RUPTURE. 
This is the greatest computed stress in a beam under a breaking 
load. 
MODULUS OF ELASTICITY. 
This is a factor computed from the relation between load and 
deflection within the elastic limit, and represents the stiffness of the 
wood. 
LONGITUDINAL SHEAR. 
This is the stress tending to split the beam lengthwise along its 
neutral plane 3 when under maximum load. 
i Run made Mar. 5, 1908. 
2 Some time after the treatments were made it was reported by the treating-plant officials that the ther- 
mometer giving this reading registered 40° F. too low. 
3 Plane between upper and lower halves when beam is horizontal. 
