TESTS OF WOOD PRESERVATIVES. 3 
mechanical and physical defects, was used. The pieces selected for 
test were 12 by 26 by 14 inches. These were cut and numbered as 
_ shownin A, Plate I. Some of the test specimens were left untreated; 
others after treatment were recut and renumbered as shown in B, 
Plate I. 
The uses to which the specimens were put are given in the de- 
scription of each test. 
CHEMICAL AND PHYSICAL PROPERTIES OF THE PRESERVATIVES. 
The chemical composition of each preservative, its specific gravity, 
viscosity, odor, flash, and burning points were tested by standard 
methods. In all distillations the apparatus described in Forest 
Service Circular 112 was used. 
The specific gravity was determined chiefly by a hydrometer or by 
a Westphal balance. Viscosities were obtained by using the Engler 
_ orifice viscosimeter at various temperatures. The flash and burning 
' points were determined by heating the preservative at a rate of 2° C. 
_ per minute in an open flash-point tester, passing a small flame over 
_ the surface every minute. 
METHOD OF TREATING WITH PRESERVATIVE. 
© Pieces Nos. 4, 5; 6, 7, 12, 13, and 14-2 were treated with the 
_yarious preservatives in an impregnation cylinder. Before treatment 
_ they were oven-dried at 100° C. in order to be sure that all speci- 
mens were as nearly as possible in a uniform moisture condition. 
' They were then weighed and impregnated. The simplest proce- 
dure of treatment was followed. For example: After the wood 
_ was placed in the cylinder the preservative was admitted, displacing 
the air, until the cylinder was completely filled; a pressure of about 
~ 50 pounds per square inch was then applied until the desired absorp- 
” tion was obtained, when the cylinder was drained of excess preserva- 
_ tive and the specimens removed and weighed within 24 hours. When 
_ necessary higher pressures than 50 pounds were used. 
STRENGTH TESTS. 
Pieces 1, 2, and 3, which were not treated, and 4, 5, and 6 (see 
_ A, Pl. I), which were treated with the preservative, were tested in 
bending to failure in an ordinary 30,000-pound testing machine, 
using a center load over a 12-inch span. Care was taken to have all 
specimens at approximately the same moisture content at the time 
of test (about 6 per cent) by allowing them to remain in the laboratory 
until they no longer absorbed moisture from the air. Specimens 
treated with oils usually contained a little less moisture than those 
untreated. After being broken, 3-inch specimens were cut from each 
end for fungus-pit tests (see B, Pl. I). 
